How to afford building a house and buying land today?

I also took a long time to come to terms with the idea of financing 32 years. But for that, we have a full repayment loan with a fixed interest rate and a very comfortable installment. Renting a house today already costs about the same, in 20/25 years our rate will be a joke when compared to rental costs then.

A fixed interest period of less than 25 years would not have been an option for us personally, we are too security-conscious for that.

How old are you?
We also only started in our mid/late 30s.

It is simply the wrong way of thinking to view credit as bondage and want to get rid of it quickly. At times of 8%, okay, people approached it differently, but at 1-2%... That is less than inflation, so you could say as long as you have a loan, you are making a profit with it - to put it bluntly. Currently, there is nothing better than taking on debt. And at 2% repayment, 4k net is enough around Berlin.

Back in the days of 8% ok, people were different

Not uncommon for 40 years...

I can understand that a long commitment and the large sums are intimidating. Just write down the opportunity costs for yourself. Then the decision will become easier. The construction costs are so high because many people are currently building and the good craftsmen are becoming scarce. From my point of view, this is an indirect consequence of the low interest rate.

So the 250k would be purely for the house? That is certainly possible. Ours (150sqm, 2 full stories) is roughly in that range. Why do you want to pay off the loan as quickly as possible?

Rarely on 40 years...

Really? My parents paid off the loan in 15 years and at the time had set a maximum target of 20 years. Nevertheless, the interest paid was almost as high as the loan itself.