If everybody was cowed by the simple fact that they can't succeed, then that one-in-a-million person who can succeed would never take their shot. So I was sure as hell going to take mine. But if the chance that one person can save the world is one in a million, then there had better be a million people trying.

I want to upvote about twenty times for this phrase alone. I suspect that your psychology was very different than mine; I think I crave stability and predictability a lot more. One of the reasons that "saving the world" always seemed like an impossible thing to do, like something that didn't even count as a coherent goal, was that I didn't know where to start or even what the ending would look like. That becomes a lot more tractable if you're one of a million people trying to solve a problem, and a lot less scary.

However, idealism still scares me. I remember being a kid and reading about communism and thinking that it really ought to work. I remember thinking that if I'd been a young adult back before communism, I would have bet my time and effort on it working. And...it turned out not to work. Since I probably wasn't any smarter than the people who tried to make communism work, how could I have any better of a chance at coming up with something valuable? Better to focus on small things, one at a time, and rely on the fact that however convoluted and mess-up society is, it muddles along and hasn't self-destructed yet. And not risk ending up doing something really awful that would result in lots of people dying.

Of course, that relies on a belief that society, which has muddled along so far, will continue to do so. There've been enough changes in the past few decades and centuries that you can make a good case for this not being true.