Batman uses his wealth to help out Gotham, he doesn't deliberately try to hurt the common people or poor. In many stories and in The Dark Knight Trilogy, he actually does donate to charity but has to stop terrorists like Joker, Bane, etc. from destroying Gotham. Saying that he shouldn't be helping to stop villains if Gotham had more money is victim-blaming. Not all crimes are committed out of financial need either, and crime is in human nature.