Why don't construction prices go down?

Not everyone received such increases.

I'm not talking about small groups or individual cases, I'm referring to the general average. IG Metall increased by a good 10%, other sectors as well. Whatever.

The discussion is pointless. Price increases never go back. Accept it and please stop clinging to details, contexts, or whatever else. Plus, it's about construction prices, not interest rates.

I can understand that it is hard to accept this fact. The human psyche is not geared for that. Moreover, it feels unfair when someone built for a good 25% less just 3 years ago. As I said, the discussion is basically irrelevant. A single-family house, if owner-occupied, is not an investment, but rather a luxury. Therefore, it's rather pointless to mourn old prices of luxury goods.

I'm not talking about small groups or individual cases, the general average is meant. IG Metall increased by a good 10%, other sectors too. Whatever.

I know that and see it with my children, where income and extras are discussed, that sometimes I almost get scared. In this respect, I simply applied your statement about €900.-/sqm only to myself and my generation and realized that this alone should not stand like that.

Price increases never go back. Just accept it and please stop holding on to details, contexts, or whatever else. Plus, it's about construction prices, not interest rates.

A serious discussion without any context will always be pointless and unrealistic.
That general prices rise numerically has not only been the case since 1990, everything used to be cheaper anyway and the grass greener. Although I was already walking on earth back then, today I only rarely have the feeling that things "were better before"; financially definitely not, but that also did not have a comparable significance in our environment in daily life.
However, most builders always had to get their money for house construction from the bank, and not seeing the respective valid construction interest rates as a context shows the dreamy, distorted picture that apparently leads to frustration.
Otherwise, one could say today everything is so great because everyone has these high salaries and not only €1,000 like before.

I can understand that it is hard to accept this fact. The human psyche is not tuned to it. Also, one perceives it as unfair if someone built for about 25% less three years ago.

From this point of view, everyone would have to feel treated unfairly because there have always been different times and situations in which individual things were better/cheaper. Unfortunately, this negative thinking already seems to be socially acceptable.
"The myth of the golden times" from a study by the IWD describes the topic of building today and back then quite well.

...it's about construction prices, not interest rates.

No one denies increased (construction) prices, at least no one I know in freedom has.
When I built in 1990, I had almost 10% construction interest, in 2021 under 1%. Why should that not be a difference, then increased construction prices almost become a minor issue (warning: joke). When I was able to re-finance back then from nearly 10% to nearly 4%, I was happy. Not seeing this whole thing in connection (context) inevitably leads to pointless discussions.

Also, one perceives it as unfair if someone built for about 25% less three years ago.

I and quite a few others do not feel that way either.
Every era has its opportunities, advantages and disadvantages, that's how I experience life; otherwise, I would have to feel unfairness in me because I have repeatedly built under completely different conditions.
My net benefits have increased by exactly 10% since 2011, so I certainly do not count myself among the haute volée, and yet I do not feel like a loser. There have been good and bad times; complaining or whining is no option for me, but factual criticism is.

A single-family home, if self-used, is not an investment either, but rather a luxury. In this respect, it is also rather pointless to mourn old prices of luxury goods.

That is a flat, by no means universally valid statement, which can also be true for you personally.
For us, it even means a high value beyond the financial aspect, namely living self-determined in our own house. Over the years, I have experienced various forms of living and now again in our own house I feel it is the optimal form for us; thus, it represents an indescribably high value for us, for which we were also willing to pay more money or forego things in other areas and do not calculate whether it pays off numerically.
Thus, it is the best investment of all for us, namely the one in our current life and especially our well-being.
From my point of view, I see unnecessary luxury every day on the street, in overcrowded children's rooms, garages, restaurants, holiday resorts, and so on, or last Saturday in the crowded shopping mall where I wondered why they were all here with their supposedly empty wallets.
As already mentioned elsewhere: the money is there, only the question of prioritization has changed.

The mortgage rates were high in the 90s, yes. However, the interest rates on savings deposits were also exorbitant by today's standards.
There were these savings bonds where you could fix your money for 5 or 10 years. They offered 10% interest and at the end even a sizable bonus.
And very importantly:
The savings interest rates were significantly higher than inflation. So saving was worthwhile...
Wages also rose significantly back then. IG Metall:
1990 6%
1991 6.7%
1992 5.4%

In the following years somewhat more moderate. But from 1995 inflation was also below 2.3%... until 2021...
This allowed one to build up equity well and then only had to finance relatively small amounts at high interest rates.

The situation was really good only for those who built around 2010 with favorable construction costs and low interest rates.
At the end of the 2010s, very low interest rates were met with massively increased construction costs... and those who built then are now being hampered by inflation... because the cost of living has risen massively.

And of course, expectations of life have also shifted. Few today still want to live, work, and forego everything else solely for their house for 20 years.

I don’t understand why people hold onto the illusion that prices will go down again. Anything that has gone up due to inflation never goes down again. Unless the state falls into a severe deflation, or there is a currency reform due to hyperinflation or similar, but then hardly anyone will be building, because in that case things will be hectic for everyone.

You only have to look at history for that. Has any price from the 90s ever come back? For any product? Nope.

One kilogram of butter cost €4.80 in 1998, €5.58 in 2007, €6.24 in 2013, €8.10 in 2018, and today somewhere around €11-13. This generally applies to everything else as well. The whole thread is simply irrelevant, in my opinion.

Basically correct, especially since wages are also rising sharply (rightly so). Material prices have stabilized; if interest rates rise again, more people will (be able to) build.

The main problem is inflation. 200 DM are no longer 100 euros but only 30 euros. You still haven’t understood that primarily it’s not the prices that have risen, but that you get less and less for the money, in this case euros.

Croatia is the best example. With the introduction of the euro in 2023, all prices exploded. And many things more than doubled. Practically overnight. Because the Croats tied themselves to a failing soft currency.

Germany had the most stable currency in the world. The DM was recognized everywhere. A monthly income was on average 4-5 ounces of gold. Today it is not even a whole ounce.

With the DM we were respected everywhere in the world and for us it was also correspondingly cheap because of our stable currency. Today we have Italian, French, or Greek conditions.

Meanwhile, Germany has the longest working life and the lowest pensions. We have the lowest home ownership rate after Switzerland in Europe. Romania has more than 95 percent ownership rate while in Germany 53 percent do not own their homes.

In this respect, it must be said that construction prices rise in euros. Calculated in gold or bitcoin or stocks, they rather fall. Possibly they also fall in US dollars. Still 20 years ago it was very popular to finance house construction with foreign currency loans.

Because building wealth, especially for the younger generation, has become difficult. High tax burdens combined with low returns naturally slow down the buildup of equity extremely. You can see that very well here in the forum. Another aspect is the declining pension level in Germany. Where before grandma or grandpa could still contribute a good amount of money, now it’s tight for many.

And whoever is lucky enough to inherit today often has to invest the family inheritance, which was built up over generations, into the new construction.

Unfortunately, the clock of life does not stop and you have to take the situation as it is. Hardly anyone can or wants to wait 20 years until a market turns.

In my view, even though it will lead to massive discussions here again, there is only one sensible way.

Invest existing equity in gold and buy physical gold every month. At least 1 ounce. I assume that in view of the further expansion of government debt and ongoing extensive inflation in euros, you will be able to build a house for under 100 ounces of gold within 3-5 years at the latest. As already mentioned, in gold terms real estate prices have crashed.

Basically correct, especially since wages are also rising sharply (rightly so) Material prices have stabilized, if interest rates make another jump now, more people will (be able to) build

My wage hasn’t increased in 5 years. The majority of employees have seen no real wage increases. It may be that wages have risen more in collectively agreed companies. But these are not the majority of businesses. Rising contributions such as care and health insurance premiums from 2025 will, alongside fiscal drag, also eat up a significant portion of the wage increases again. The once promised climate money, the increase in child benefits, or the mitigation of fiscal drag have just been cancelled. Interest rates will certainly make a jump, but upwards.