There's no point in making comparisons like these. On the other hand it's interesting to compare some of the IT-made billionaires to the traditional billionaires. Bill Gates was not born into money* but ended up drowning in them. He probably sees both the diminishing marginal utility of exorbitant wealth and the tendency of profits to accumulate exponentially. As a nerd, he's probably unable to give into a lavish lifestyle anyway, so he does the best thing of giving back. He can hope to be remembered in history for that, because, after all, how many rich people made history just for being rich?
[*] he wasn't poor, probably more than middle class; in any case, there's no doubt he's self-made
Sure, but a large part of the reason he was "self-made" was his mother's relationship to an IBM executive. I'm not so sure Bill Gates becomes the world's richest man if his mother was a teacher and his father was a plumber.
[*] he wasn't poor, probably more than middle class; in any case, there's no doubt he's self-made