Using this reasoning, Muhammad Ali should have quit boxing in 1967 rather than take the political positions he did. He missed three years when he was stripped of his title and denied his opportunity to compete while he was in his absolute prime. Many of his most memorable fights happened after the Supreme Court unanimously overturned his bogus conviction on draft evasion. Opposing the Vietnam War, advancing social justice, and bringing attention to the oppression of black people were far more important to Ali than merely being The Greatest. For him, being The Greatest involved using his platform to change society for the better, even at the cost of many more victories in the ring, millions of dollars, and the temporary approval of "mainstream" society. I agree with your evaluation of Bennett being a five star prospect  for his post-football life, but it's smart on his part to use his 15 minutes (relatively speaking) of fame, to bring attention to issues more important than football.