Odds of Getting In
Like most sports, you need to start young and keep going through all the successes and failures—hopefully more of the former and fewer of the latter. As long as your high school or college has a team, you'll be able to play organized golf for long enough to figure out if you have what it takes.
If you've got really good game, you'll make it to the last rounds of your state championships and the colleges will find you. If you're capable of playing for colleges with the best golf programs, then the coaches will find you. And so on and so forth until Nike calls to ask you what you're up to later.
But if you're talking about the odds of turning pro and actually having a life as a golf pro who makes money from winning tournaments, that's a completely different story. It's not even in the same book.