The answer to this question is simple.
Becoming super-rich requires devoting your life to becoming a great corporate leader. This means being too busy to worry too much about other things (like being a superhero). Most of the World's richest men are self-made corporate bigshots. Lex Luthor himself is a self-made man.
Batman on the other hand, was born into his wealth and position. This means although he carries the title of CEO, this is largely a token title. After all, Wayne Enterprises was obviously being well managed by someone else between the time that Batman's parents died and the time he turned old enough to run a corporation right? Batman is really just a millionaire playboy with too much time and money on his hands.
So there you have it, the reason why rich men resemble Lex Luthor is because they're self-made. It's not good but it's better than having our world run by a bunch of spoiled brats right?