I see this as sort of the main riddle (or catch-22 if you're the pessimistic type) of life. The semi-unrealistic hope of optimism is what motivates us to get things done. For the HN crowd, consider startup founders. The vast majority of startups fail, yet virtually all founders go into it overestimating their chances of success. After all, if they were realistic about their chances, they'd find the whole business too…
I guess such optimism/pessimism can be different on different levels? I.e. "Chances of that idea to work out are nearly nil, but if I allocate a non-critical amount of resources it is worth a try as if it will work out - it will be great"? Basically I am pessimistic about the chances of a startup working out, but I am very optimistic about upside if, in a very unlikely event, the idea does work. Optimistic - because idea can work, but still be a crappy result, which honestly, did happen. I.e. it sorta works, but not quite big enough payoff, requiring me to maintain it without a clear path forward. In such scenarios, I usually just slowly cut resources to it as my interest wanes over time, but I still have quite a few websites/domains from 10+ years ago which I can't push myself just to not renew one day...
EDIT: and as another person mentioned, as I accumulate more wealth, I try out more ideas indeed. But honestly, I am no more optimistic about these. Just the ability to invest allows me to try more things without jeopardizing future of my family. The toughest limit is time, unfortunatelly I still clueless how to leverage wealth to acquire time resources (so far I am very bad at hiring, no matter if it is helping to clean the house or to write code).