This is a good question! You can make millions of dollars if you make it into the NBA.
But I want to ask you how good are you at basketball? Do you absolutely dominate on the court? Are you better than everyone else? I recommend that you practice a lot if you want to make it into the NBA. Play in camps, play for your school's team, etc. Realistically it is difficult to make it into the NBA. Here is some information that will that will give you an idea of the chance of a person getting into the NBA. Players that make the jump from high school to college: 2.9% Players that make the jump from college to pro: 1.3% Players that make the jump from high school to pro: .03% http://www.hoopsvibe.com/features/285631-the-odds-of-playin-in-the-nba
I don't want to discourage you from trying to pursue your dreams. For all I know you could be the next Kobe or Lebron. But also look into other things perhaps you can get into sports broadcasting, become a basketball scout, athletic trainer, etc. These are all obtainable goals!
Best of luck! Ben