Bruce Wayne inherited his fortune. He is the heir to a fortune estimated at nearly seven billion dollars. This wad of cash was built over hundreds of years by his family before him who were merchants and then shipping tycoons. Eventually they diversified into manufacturing and chemicals, expanding their empire and their influence until young Bruce was the sole beneficiary of all that multiplying millions. How does Bruce choose to spend his ever-expanding bank? Well, there's the Wayne Foundation, which is dedicated to the elimination of trafficking and exploitation of children. A bachelor himself, Mister Wayne continues to find ways to make his money work for him and his community. He has even adopted a young ward, Dick Grayson who was orphaned like Bruce at a young age, and helping him find his way in a cruel world.
Tony Stark is also a child of wealth. He grew up in the shadow of his father, the founder of Stark Industries. Howard Stark was a mega-capitalist in the style of Howard Hughes. Except instead of aircraft, Stark's diversification ended up making piles of cash in the weapons industry. Young Tony grew up in a world that went boom. When his father passed away, that's what Tony Stark inherited. It wasn't until he had his own up-close and personal interaction with shrapnel that he began to reconsider building his roll with things that explode. His focus on alternative energy sources and artificial intelligence, some say, has helped him "privatize world peace." That, and he's Iron Man.
These multi-billionaires have found ways to move their bank accounts around in ways that give back to the world around them. Though there is no solid evidence, some suggest that like his Big Apple counterpart, Bruce Wayne is rumored to have connections to Gotham City's vigilante crusader. Fighting crime and subduing evil in a very hands-on way shows how dedicated these gentlemen are to leaving the world a better place than how they found it.
Donald Trump's net worth is estimated at just a shade below Stark and Wayne. What is he doing to make the planet safe? Well, let's just say that he isn't building bat caves or designing suits of armor. He reminds me less of a super hero than - well - Lex Luthor. Which may explain that whole hair thing.