Did I miss something? He explicitly wrote that he will not go into the reasons for the move and that the new house is simply "nicer, better, more fitting." Quality of life, the financial aspect is just a "if we even earn 8,600€ net like in the past, can we then afford 4,000€ for the house including incidental costs?" .
Yes. He is still afraid of a wealth tax (if not here, then it was in another thread). As I said, purely for consumption reasons you can do it like that, but then you could do almost anything. Then you could also drive a Porsche instead of a VW, Louis Vuitton instead of a common brand, etc. It then no longer concerns practical use. However, once the financial side of a deal is to be evaluated (and that is actually what this forum is for), other criteria are factored into the calculation. And if the only argument left is: "then it will be sold if necessary, you don’t go into private insolvency with your equity," then to me, that’s quite a naive perspective. Perhaps also due to the perspective of a bank advisor who earns his money with mortgage loans.
Even if only the consumption perspective counted, with this income I wouldn’t want to put 50% into my house, but would have other wishes that would then have to be reduced accordingly. But that’s an individual preference and merely a food for thought. Only the original poster can decide that.