Trouble with giving to charities is it's not very personal. Ok you may increase the world's anti malaria budget from $1.5bn to $1.50001bn but you can't turn around and say look at this cool thing I built.
Building a cool thing and changing the world are two very different things. Some individuals sincerely believe that working on any startup is intrinsically altruistic and 'changes the world' - Silicon Valley (the TV show) lampoons this and correctly so. You are not "making the world a better place through minimal message-oriented transport layers"
Although the things that have changed the world have generally been cool. Tech like the electric motor, jet aviation, the printing press. Also intellectual works like those of Keynes or Marx. Less so with charitable donations. Personally I'm thinking of trying stuff and figure I've got more of a chance of making a difference by innovating rather than donating a bit.