From Jack Johnson, to OJ, , to Barry Bonds to Michael Jackson, to Tiger Woods and probably to Barrack Obama. (And a lot more in between.)
What do these men have in common?
Each of these men were seen as anomalies and as a credit to their race.
Each of these were set up to be role models and examples of what is possible.
But each of these men were/are still human.
Each of these men had/has flaws.
But why are their downfalls so "newsworthy"?
The simple answer is that their downfalls were to be expected.
Their successes were not seen as the norm, and each was expected to return to his "natural state".
So when these anomalies are returned to their natural way of being - those who were jealous could quip, "I told you so.".