There are many good golfers out there. In order to become a golf pro you really must be great at golfing with outstanding scores. Enter tournaments and work your way up from there.
The best way to become a professional golfer is to be really good at golf. If you practice long hours and improve enough to compete with professionals, then you can enter tournaments and begin competing. That's all there is to it.
You need to have a reputation as a good golfer, which means going professional. You need to be good, and then when you hang up your clubs and retire you will get a chance to work at a country club.
The course to the either the PGA or LPGA is filled with thousands of hours of pratice and rounds of golf. Followed by an attempt to attend and successed at Q school (pga required 'training"). If one successed at winning your card at Q school you are a golf professional