Is Bill Gates really an example of what the person described? Correct me if I'm wrong but I don't think his motivation for working or making money was to donate it. It seems like he decided after accumulating his wealth that he should use it for good.

It seems important to note the difference because I don't find it hard to imagine how a person whose motivation is to help the public good might not be passionate about a job which doesn't inherently do "good".

It's hard to speak of motivation unless you're the person in question. Most people do things for a number of different motivations. Hence the adage "We judge ourselves by our intentions and others by their behavior."

I suspect that as far as Bill Gates is concerned, he considers it all a game and just wants to win. For the first half of his life, the game was maximizing the money he makes. For the second half of his life, the game was maximizing the money he donates. This is all just suspicion, though.

Did Gates ever speak of this? If not, it's a terrible example.

Plenty of rich people, after spending their lives in business, eventually switch to philanthropy. Presumably because they discover, like the OP, that they value doing something more meaningful than stacking up money. But that's entirely different than somebody who has that realization young and does corporate stuff as a way of extracting cash, which is what alwaysdoit was suggesting.