I am here with you on this one. I have been a programmer since I was 13, that made me a generalist developer who likes to jump into many different things, because building stuff was my "toy", my entertainment. And every toy gets old.

I am almost 30 now. I feel it gets tougher to be a generalist as any industry matures. Take Frontend / Backend development, versus Web Developer of the past.

Frontend Development alone has become more complicated than the total mental load a Web Developer would endure delivering both backend and frontend.

In that moment, as a generalist, as suggested above, you find yourself without a foundation, but rather crumbling ground. You better know how to fly.