While Bruce Wayne was characterized as a wealthy socialite from his first appearance in Detective Comics #27, his parents—who didn't even get a mention until six months later—were little more than just a pair of highly motivational corpses. By 1956, however, Thomas Wayne had been fleshed out a little more, and given an occupation: he was a doctor, specifically a surgeon.
On the one hand, an accomplished surgeon in a major metropolitan city can pull down a considerable amount of money. It opens up some pretty interesting potential for stories, like Bill Finger and Sheldon Moldoff's "The First Batman," from Detective Comics #235, where he's kidnapped by gangsters who want him to dig a bullet out of their boss, which sets a chain of events into motion that culminates with the Waynes being murdered in Crime Alley. On the other hand, unless you're a good enough doctor to literally invent immortality, you probably won't be getting a big enough salary that your kids can buy bat-shaped space shuttles.
With that in mind, a story in Superman/Batman #50 gave Thomas Wayne another way to earn some extra cash. According to "Fathers," Thomas Wayne stumbled across a probe that Superman's father sent to Earth in the days before Krypton exploded, and not only did he use it to telepathically convince Jor-El that our planet was a great place to send his kid, he reverse engineered its alien technology to give Wayne Industries an edge and save the company from bankruptcy. If that's the case, Batman not only inherited his money from his parents, but from Superman's parents, too.
