Sole earner with a desire to build a house

For me, that would be achieved if we were dependent on government transfer payments

And how do partners and children see it, how about the social environment?

It is easy to say you can live without all that "luxury," but actually doing it is a whole different story. There are certainly people who can do it well... but they mostly don’t even get caught up in the rat race in the first place.

To my knowledge, the principle of BU exists almost only in Germany

That is not correct. It is certainly regulated a little differently in every country (also depending on the presence of government security) and sometimes more or less affordable/extensive, but certainly not a unique product of "German angst." Try using the term "income protection insurance," for example.

Has no insurance company noticed this market gap yet?

And why don’t they build airplanes out of the material of the black box?
*X-Files music plays*

As you already rightly said, everyone has to decide for themselves – after all, it is a voluntary insurance. I just wanted to point out here that one should inform oneself beforehand in order to be able to put oneself in a position to make a well-considered decision in the end. Phrases like "until I am BU in my job..." or "they don’t pay anyway" are, on the other hand, a clear indicator that the respective originators have not done this.
That’s okay, but unfortunately, they then have nothing to contribute in terms of content.

Thank you for starting the BU discussion!! I will now take a closer look at BU (especially for coverage during the financing) - on the expense side I forgot one item / hobby: motorcycle (about 600-700 euros per year). This will certainly make the alarm bells ring even louder regarding BU / RLV.

Besides some coverage from our savings, we would certainly also have some coverage from our parents amounting to about one annual installment or a bit more...

My husband works in the IT industry. Nevertheless, he obviously has a disability insurance (BU). He was the main earner for some time while I was finishing my studies and hardly worked on the side because of our small children. I will soon also take out a disability insurance for myself. Overall, we want to insure ourselves in such a way that we wouldn't have to sell the house in case one person becomes unable to work, or at least not immediately. As long as "only" one of us became disabled, we could still live quite comfortably. Insuring both incomes in full would, however, be too expensive for us.

I also find your situation okay since you have a lot of equity. The rest has already been said.