How to afford building a house and buying land today?

I don’t know if I’m too stupid to understand this calculation.

You spoke of 10 years, which I took as the basis for my calculation.

If I enter these numbers into an interest calculator, the result is:
Interest paid after 29.5 years: 127k euros

Yes, after 30 years = paid cold rent of the owner.
In 30 years, as a tenant, you pay 875€ x 12 months x 29.5 years = 310k€. So the tenant pays in 30 years (I calculate without rent increase, which is unrealistic) about 2.5 times what the owner has to pay. But the owner has a house and you only have an apartment.
Find the tenant’s mistake

You can set aside the 30,000 for maintenance and renovation.

That’s possible too, but nothing happens in 10 years. With new construction, you can expect renovation measures from years 20-30. Cosmetic repairs are the same as for the tenant.

Why has the owner achieved a savings performance of 110k euros and the tenant not? Is that money in your account or is it again some fictional performance caused by inflation and low interest?

Because the owner reduced his loan in 10 years from 400k€ to 290k€. So he increased his assets (house value remains constant) by 110k€. You as tenant have to, in order to have the same increase in assets after 10 years, besides your monthly rent of 875€, also make a savings effort, probably in the amount of 700-900€. So you spend significantly more for the same result after 10 years than the owner.

And why should an owner save more than a tenant? That all depends on the monthly savings rate taken from the salary, or am I wrong? And that in turn depends on the salary and the saver’s willingness. I don’t deal with fictitious and theoretically saved money.

The owner is forced to save by the bank. The tenant has to overcome their inner weaker self and reduce consumption in favor of a savings rate (amount see above). You can do all that. BUT: The average person does not do it.
That is the problem or the reason why the owner can usually live better in old age than the tenant.

I tell you honestly, just for house costs and interest I can easily live in rent in our area for 40 to 50 years (800 - 900 cold) without restrictions

That this is not entirely true, you can take from my calculations. The cold rent = interest payment of the owner is lower than your cold rent to the landlord, combined with (subjectively) higher living quality.

Then I’ll fall into the grave and had no stress

Who has stress? Problem for you can be that as a tenant you do not provide for old age and then have to pay rent for 20 years in retirement, while the owner sits in the paid-off place. Or even better moves into a small condominium and then can spend the surplus assets without having stress during his working life.

Correctly calculated, it is approx. €75k interest and not €110k. In addition, as the owner you have provided almost €110k in savings.
During the same time, you pay €105k cold rent – so more than you pay as an owner cold = interest. Do you also save the same amount additionally?
For the €30k extra you pay (without rent increase), I, as the owner, easily go on vacation every year

Personally, I call that creative accounting. Because in that time you have (hopefully) already saved a good part of the €30k "left over," or spent it on maintenance.
After 10 years, you’ll likely need a heat pump. Modern gas heating systems are also no longer durable.
Thinking 20 years ahead, you’ll also have to replace the windows.
The garden is always good for expensive projects. Or repaving once in a while.
These are costs that a tenant mostly does not have in this form. If at all, then through rent increases.

A homeowner does not save compared to a tenant. As long as the owner does not live in the house, a house primarily costs money.

Whether the tenant actually saves or not is irrelevant. In principle, they could.
And YES, these are apples and oranges.
The tenant simply doesn’t have a garden or yard. It is a different (for me better) way of living than in an apartment.

But claiming that the repayment on a house counts as a savings rate is, to me, an absolute myth.

But that you count the repayment as a savings rate for a house is an absolute myth to me

Hehe, debt-free property for retirement is a myth? So as a tenant you save so much that you can pay for a house in cash at retirement? I don't consider that a myth, but it is the reality for 90% of tenants.

Well, I can't just say I've saved money because I paid off my debts to the bank, I've never heard anything like that before. That's what I meant by fictitious and theoretical savings capital. You can't buy anything with that.

And the value of a house usually doesn't stay the same. Especially not over decades. The prefab box houses nowadays start to mold inside and out after 15 years. So you can be glad if the place is still habitable at retirement age.

I have to say, no reasonably thinking person can take your calculations and arguments seriously. That living easier in old age just because you have paid off a house is also a fictitious rumor. Just because I, as a tenant, don't give the bank 120,000 euros in interest doesn't mean I don't invest in retirement provision. But you can do that differently too. This is all very generalized here from you.

But that you consider the repayment of a house as a savings rate is an absolute myth to me.

However, that is exactly how my financing is structured. The initial interest rate corresponds to the monthly net rent, the repayment slightly less than the old savings rate.

Well, I can't say I've saved money just because I paid my debts to the bank, I've never heard anything like that.

What do you call it when you own a house after 20-30 years? The money has to come from somewhere for it to be YOUR house.
Then call it building retirement provisions.
Or is it not saving for you if you pay money to the bank as a savings plan, or to the insurance company, or as a stock savings plan? In the end, it always results in asset formation. It is not saving if you only pay money as rent to the landlord.

That’s what I meant by fictitious and theoretical savings capital.
You can't buy anything with that.

No? You can’t buy anything with a debt-free house? Is the house after 30 years just theoretical or actual assets (regardless of the price you get when selling it)? Am I currently living in theoretical assets? When I touch my debt-free walls, it feels pretty real to me and my family.

And the value of a house usually does not remain the same either. Especially not over decades. The prefab boxes nowadays start to mold on the inside and outside after 15 years.
So you can be glad if the shack is even still habitable when you retire.

Then you have no idea about real estate, let alone prefab houses. Sorry, but that is complete nonsense. Just have a look on ImmoScout. There are actually houses and apartments that are 30 years and older and still habitable...

I have to say, no reasonably thinking person can take your calculations and arguments seriously.

Are you one of those yourself?

That living easier in old age just because you have paid off a house is also a fictitious rumor. Just because I, as a tenant, don't give the bank 120,000 euros in interest, doesn’t mean I don’t invest in retirement provisions. But you can also do that differently.

No, you give your landlord a multiple of what I throw into the bank’s throat in interest. Ever thought about that?
Of course, you can invest in your retirement provisions differently, but you have to pay diligently for that too. Do you pay as much as in my calculation example? Do you have a 1:1 housing comparison between your small apartment and a larger and subjectively nicer house?
If you save well, that’s okay—but you have to do that. And many people currently do not. They live “cheaply” renting and spend their money. They are also not forced to save like the homeowner is.

Unfortunately, I have not yet received any well-founded arguments or calculations from you that support your statements. At most fairy tales or rumors—basically alternative facts without evidence. By the way, it is statistically proven that people with property live easier and have more money in old age. Just saying.