Well, first of all the legal system gives lots of leeway to people who are outrageously rich. People with that much money can afford to get a lawyer like Tony Montana's in Scarface, who's good at putting a reasonable doubt in the minds of the jury and such. Just look at OJ, if he didn't have millions of dollars to throw at his lawyers, if he was just an average guy, he'd have been executed by now.
And as for why people look up to them, Grand Theft Auto: Vice City put it best; "without gross symbols of excess, what will Americans have to look up to?" There will always be people who look up to that I suppose, and no amount of legal issues will change that.