Is a single-family house in the Stuttgart metropolitan area still affordable?

Yes, you were very variable. Depending on the thread, you presented different scenarios why you/you guys are simply perfect.
Sometimes great income and built everything yourself.
Sometimes great parents who love and give you a lot.
Sometimes normal income with part-time because time with the kids is much more important than earning a lot of money.

By the way, I am now withdrawing from this forum because our house construction is completed and I see no reason to voluntarily have to annoy myself

You only registered in the forum after you were already finished. Strange to use that as a reason for leaving now...

We’re doing great, we both completed two degrees with top grades, both have doctorates, healthy children, great parents, and are very happy as things are. I owe no one any accountability for anything

No, you don’t. But no one’s asking anyway.
From personal experience, I find people who have to mention such things over and over suspicious.
But I don’t want to accuse you of anything. It’s probably all true and you just like to talk about it.

I think it comes down to some people inheriting, some not. Those who inherit a lot usually also earn a lot of money, which is probably systemically caused (wealthy parents, good neighborhood, easier access to grammar school, private university in Friedrichshafen or somewhere else, good job, somehow dad knows someone at Bayer or Covestro after all). The "Winners Bias" is also linked to the idea of having worked everything out "by oneself." (I'll just say we call "BS BS!") but that's how it is. And when the financiers of the private university pass away, they inherit 3-4 multi-family houses. But that also comes with a lot of responsibility. and the stress of management.. Be glad that you... "Yes – transfer everything to me, I gladly take on the heavy responsibility

Education can be bought, unfortunately still proves to be the truth.