How to afford building a house and buying land today?

Nobody wanted that then or wants it now. It is sheer desperation, and that still exists exactly the same today.

I understand what you mean. But, if you already talk about necessity, 5 children were also not a necessity at that time...

Back then as now, in the end, to a large extent, everyone is the architect of their own fortune.

So I can still accept a tax back payment

I don’t. Not in the sense of "it has to be immediate and clearly four figures." First, you’re not helplessly at its mercy but can quite well influence what comes out in the end by choosing your tax class, and second, it’s not like it ambushes you without warning – you find out the rough result when you do the declaration. So, especially with known back payment risks (e.g., parental allowance or unemployment benefits in certain constellations or very unequal incomes) you simply do the declaration in March and can then leave it lying around until the end of July if necessary. And THEN it still has to be processed… And I have NOTHING left at the end of the month and can still be spontaneous and sociable. And I have an iMac (besides an iPad and iPhone). Because all of that is priced in. That’s how I plan to keep it at home too.

I understand what you mean. But if you already talk about necessity, 5 children were not a necessity back then either...

Then as now, in the end, to a large extent, everyone is the architect of their own fortune.

So I don’t believe my parents were unhappy. They would have liked to continue living in the rented house but were not opposed to the idea of ownership either... they would have just approached it later. For that, they were done paying it off by around 50 and now enjoy their life accordingly more.

In the past, everything was different, especially in the countryside. There were no rental apartments, people always built XXXXL houses, land was cheap, neighbors helped each other. That is why there are cheap houses all over the villages. Why? No one wants to maintain the XXL houses anymore, parents go to care homes, children move to the expensive urban areas.

I understand.

You rightly assume somewhere that there is "enough" money. So, maybe not immediately, but it will come in eventually.
If the financial situation looks like you describe, meaning one can save for it, etc., then that is a legitimate matter. I don’t argue about that either. Everyone has to define their own limit and deal with it.

But if a financing is calculated to the extreme at all costs and in the end there is no saving possible, then in my opinion that is an absolute wrong decision to buy a house. Even if it "actually" fits.

Anyone who can just manage the unavoidable necessities at the lowest level and ends up with a 1€ surplus at the end of the month is overstretching themselves. We agree on that.
Personally, I have my standards (for example with cars, clothes), I don’t want to have the cheapest option. I also have an expensive hobby that I would not be willing to sacrifice for a house. If I factor all that into my household budget, I still end up with a surplus from which I can pay for vacations, or afford other luxuries, or build savings.
What everyone considers a luxury for which they want to spend their surplus, or what they consider unnecessary frills, can be debated endlessly.

Everyone should honestly look at their own lifestyle. What is important to me, what I don’t want to give up. Then keep a household budget and see what is consumed per month for the desired "standard." And only what is left over is surplus.

By the way, for me it is like this: without buying a house, I would still be working part-time (it was 90%, which is quite a lot, but now 100% makes a noticeable difference both in time and financially – the latter mainly because this money is 1:1 surplus), and I have also reduced my hobby expenses somewhat. The house was worth that to me.