How come a Player like Lebron James is so Rare in the NBA?

Guys in Football cannot crossover to the NBA because a lot of them lack the skill of an elite basketball player. I'm sure a lot of them tried during their college years but basketball requires a lot more than the body of a football player. LeBron is a rare speciman due to his ability to move at freakish speeds for his size, the ridiculous vertical and the good hands of a ballhandler. The ability for a slightly big man to handle the ball, defend, make plays and create offense is very rare in the NBA and thats is why he is coveted so much.