Ever since the NBA Draft started trending much younger, a lot of those young players have been a gamble. Think about guys like Leon Smith, who was in no way emotionally mature enough for the NBA as a teenager and Kwame Brown, who was the #1 pick in 2001. He survived for 12 years in the league but was widely considered a bust and his early teammates were struck by how unready he was for the world of his chosen profession.
The league has gotten better at figuring out bad bets in many ways and spending year in college, for most players, helps maturation, if only marginally.