The aspect of being bored, ran out of challenges after all these years, is probably very important here for me. Thanks for pointing me on that.
I wouldn't be naive as founder, also thanks for challenging this, important point. I successfully created a startup as employee before ("Intrapreneur") and know all the tools, incl. several ways for validating early business hypothesis by customer research. So no danger here, thanks agin, good point to think about.
When I reflect on your post I feel that I like business-challenges more than coding-challenges. I also have already proven that I can do good business decisions, one of my business models worked out. The thing is, good deciding alone is worth nothing. Business people don‘t take me for serious. I lack the loud way of talking, the "loud" way of sitting/walking/standing, the ignorant way of neglecting failure, I even avoid looking into faces (a bit, not entirely) etc.
I seriously thought about taking actor's lessons. So I can learn how to appear like a manager ...

Well, there might one way out: I could start small and make myself independent from venture capital and blown up managers by choosing a niche business model in which mostly the customer satisfaction defines my success. Then I wouldn't need actor's lessons or worry about being rejected and cut off capital supply because of my schizoid nature. Like selling very special electronic devices in low volumes to customers who really love this devices. (Electr. devices is what I know most about). Also this way I can start small, keep my main income stream up and running in parallel, so the family is save.
So this way I would avoid a management position (see thread title ...) and I would still be able to play business challenges.
Thanks a lot again.