Insecurity was the reason behind Kevin Hart's decision not to take up the role he was offered in 'Tropic Thunder' - but at least he's had the courage to admit it. Hart had the chance to play Alpa Chino in the comedy film, and was initially enthusiastic, but ran away from the production when he found out that his character would be gay. He didn't feel like he could 'commit to' playing a gay man on screen, and so withdrew from talks.
Since then, Hart has confirmed that he has nothing against gay people or the gay lifestyle, and that his inability to take on such roles says more about his own state of mind than anybody else's. He's stopped short of saying that he'd approach things differently now, but his more recent statements at least suggest that he has a little more emotional maturity than he used to.