The guy has three World Championship rings and an Olympic Gold Medal. That should be the end all, be all for the sake of the question posed.
Yes, he hasn't won a title without Shaq. How many titles did Shaq have before Kobe? Exactly. They needed each other. Shaq need D-Wade to get himself another ring. Shaq has never done it alone, either.
Still, he has those rings and a gold medal. As much as you hate him, you really can't say that he can't win the big one because he has.
Now you can make the argument that he hasn't been able to win since Shaq left and hasn't been able to win the big one "carrying the team by himself" but that shouldn't discount what he's already done in his career.
Look, I think he's a smug, self-centered pr*ck. I hate the Lakers and hope he never wins another ring in his life. However, when it comes to the winner question, I have to swallow my hatred and accept the fact that this guy has won in his career.