re: PGA players usually peaked aged 30-40

It's really very simple, these guys come out young and they're grinding, hungry, and working hard to win. They have success, get older, get married, and get soft. They lose that edge. Oh, they probably think they are still working hard but they're not.

Their wife may not understand just what it took to reach those level, they demand a little more of their time. Then kids come along, takes more if their time. Then there are the responsibilities of sponsors, appearances, commercials, it all takes time away.

Lose that edge and start to slip. Only if the player figures out how to juggle all these things, or reprioritize, will they have success again.