Comics

When you have Joker, Bane, Ra's al Ghul, Penguin, Scarecrow, Killer Croc, Riddler and Victor in the same city you're literally risking your life if you go out every night to fight them (and they are FAR from poor), especially with what Gotham police is doing. And besides, he's doing a lot using wealth for philanthropy and supporting Gotham, even his parents did. That unfortunately isn't shown a lot in movies but another notable example is when he gave his entire house for orphanage. Unlike Tony Stark who is presented as philanthropist but actually doesn't give much of a shit or you know, a literal best example of a realistic billionaire you're looking for: Lex Luthor.