Your stated assumption was:

  I'd assume that intermediate and experienced C++
  developers are probably older on average, and are
  unlikely to be interested in developing games.

And that is an incorrect assumption. A non-trivial amount of current game development is done in C++. Couple that with the fact that to have the games considered "AAA" on the market now requires advanced techniques employed in the language producing them and that C++ is a frequent choice results in the invalidation of your statement (not harshing you here BTW).

It doesn't hurt my case that I am an experienced "advanced C++" developer which makes video games either tho ;-).