Is building a house realistic for us?

Yes, that's the case with the OP. I also said that financing that much would be too much for me.

But to me it sounded as if you directed your statement at Sturkopf86 or said in general that after the construction it will "always be tight on cash" or that you cannot build with 4,500 EUR net without getting into financial difficulties. You can't say that in a general way. If you were well advised by your bank, you should actually not get into financial difficulties.

You can clearly see the insecurity from the OP. And it is not certain that 500k will be enough. So now

I've quickly calculated it:

If you want to finance 460,000 EUR over 20 years at an assumed interest rate of 2%, you would have a monthly payment of about 2300-2400 EUR. But the bank has probably already told you that or it has even been mentioned here in the thread.

Whether you can and want to afford it is something only you can decide. I think it's quite a lot, but you have a good income.

I mean, TE didn’t just graduate from university three years ago or anything, but despite a family income of 6000€, they have only saved 40T€ in equity. So the savings rate is practically zero. Where has the salary gone over the last 20 years? Personally, I don’t care about that in this case; after all, money is meant to be spent. You just have to be clear that it can’t keep going like this. Of the 72,000 annual income, 10,800 has gone to rent so far, but now suddenly 28,800 is supposed to be spent on housing (loan installment 2400€). That means from now on only 18,000€ less can be wasted per year. (This corresponds, for example, to three luxury holidays costing 6000€ each per year...) That will be a cut that you can feel.

Yes, I agree with you. My brother-in-law is a banker, he says banks always look at the savings rate and lifestyle as well. There are clients who have 8,000 EUR net income but waste most of it on their luxury lifestyle. Such clients would be less likely to get a loan despite the income compared to clients with only 2,000 EUR net income who have relatively low expenses and a regular and relatively high savings rate. I also wonder how someone with such an income and in their early/mid 40s can only have 40k equity. The banks will wonder about that too.

Yes, I agree with you. My brother-in-law is a banker, he says that banks always look at the savings rate and lifestyle as well.
There are customers who have 8,000 EUR net, but squander most of it on their luxury life. Such customers would rather be granted less credit despite their income than customers with only 2,000 EUR net who have relatively low expenses and a regular and relatively high savings rate.
I wonder how someone with such an income and in their early/mid 40s can only have 40k in equity. The banks will ask themselves that, too.

Hello, your brother-in-law seems to work at a small savings bank. The big institutions/banks check according to a standard procedure. They are credit factories that check and approve loans according to the same scheme. No one will discuss equity or consumption behavior or warn customers or give advice. Purely from the debt service perspective, the loan will work, unless the credit rating is lousy. And regarding the 2,400€. The installment is one thing, often the ongoing additional costs are forgotten, which can be 400€ per month here. So almost 50% of the net income is gone. Good luck

Yes, I agree with you. My brother-in-law is a banker; he says that banks also always look at the savings rate and lifestyle. There are customers who have 8000 EUR net but spend most of it on their luxury lifestyle. Such customers would probably be given less credit despite their income than customers with only 2000 EUR net who have relatively low expenses and a regular and relatively high savings rate. I also wonder how someone with such an income and in their early/mid-40s can only have 40k in equity. Banks will probably wonder that too.

I don't know anyone whose private consumption was investigated. How is that supposed to work? I consider the above statement to be complete nonsense.