It is my understanding that this really is quite dangerous due to Wildlife (gators or crocs depending on where you work) as well as chemical/pesticide runoffs.
No personal experience.
Yup. There was an article about it that I read a couple years ago. There are health concerns due to chemicals and wildlife (you’ll want to take some shots).
It’s competitive. Divers have agreements with courses to dive their ponds, etc.
Poaching golf balls is a thing. Divers have shown up to “their” courses and found the bodies of water picked clean.
You have to recover a LOT of balls to make much money at it.