Oldest age to turn professional

I think there are two scenarios in which that can happen:
a) you have been a very good amateur golfer for most of your life and played in high level competitions, just never had the means, time or desire to turn pro, because other things were more important, but now you feel like you can make it happen
b) you have been or worked towards becoming a professional athlete in another sport like hockey or football, but can't continue on that path due to an injury or the like

I don't think someone will pick up a golf club for the first time at the age of, let's say, 35 and become a playing pro later.

Also, I think it is more unlikely to happen today than it was maybe 50 years ago, because the game has become so much more athletic.