Optimism = fantasy, pessimism = reality. Not many people like reality so they focus their thoughts only on the fantasy. Look at people who believe humanity has no faults and will change for the better. Look at people who want to "conquer the stars". Tell them any amount of realism and they'll attack you like a pack of hyenas.

I know a person who is overly optimistic it isn't even remotely realistic. He's convinced that humans will conquer the universe in the future, live where it's uninhabitable for humans, and everything will be just like in the movies. Flawless space travel. Reality: Humans can only live under certain conditions which happen to be right here on Earth. We don't need any sort of extravagant needs to sustain us.

They compare space travel to the days of Napoleon. They're forgetting that he and the other early explorers were on Earth where the survival was very much guaranteed. The most asinine comparison ever.

Well, whatever, some folks just have to learn the hard way.