True, a lot of players do a 5th year at prep school.
It's crazy how private schools are being run as athlete factories.
Oak Hill (where hundreds of NBA prospects attended at one point or another, included Kevin Durant, Mike Beasley, Nolan Smith, Brandon Jennings, etc) supposedly has a total of 100 students including the basketball team.
I think Mount Zion (Tracy McGrady's old high school) was being investigated for letting the students practice ball all day and not do any real work.
Actually, everyone at Oak Hill is a basketball player (JV, Vars, Freshman, Soph for boys & girls) & virtually all were recruited. I visited my junior year in HS, it's pretty much basic SAT & ACT prep for a few hours with intense tutoring, then practice & weights for the rest of the day. I don't even think anyone pays to go there, you're just expected to give a certain amount back if you go pro. But if you're there, there's a 75-80% chance you're going pro somewhere.
It's not a bad situation for someone whose only opportunity is ball. Schools like that are in the minority though, most of them are like CTK & Rice, where the players really only report to the program but are still responsible for maintaining grades.
The main reason why most of the high school phenoms never make it is because of their "agents", over zealous coaches & money hungry family are the first ones to take you out. You get caught up cutting corners trying to get ahead or because they have bad personalities. Talent ain't sh*t if people don't like you - greatest thing I ever learned from ball.