Free agent forward Kenyon Martin claims that he hasn't been picked up by a team yet because of his brash personality. While that probably isn't the only reason, Martin's history is sure to give a few teams pause.
Players with uncontrollable egos can be found by the dozens in today's NBA. In most cases, an individual's performance on the court outweighs whatever headaches he causes the front office, so most coaches choose to ignore the negatives as much as possible. Quite simply, dealing with superstar athletes with outsized egos is simply one the costs of doing business.
Besides...teams who lack players with big egos typically don't fare all that well in the grand scheme of things. So maybe there is something to having a few talents who believe that the world revolves around their every move.