I disagree. Obviously there’s no single rule, and we can argue about what causes what and what is just a correlation, but I think a lot of unhappy people are cy

I disagree. Obviously there’s no single rule, and we can argue about what causes what and what is just a correlation, but I think a lot of unhappy people are cynical, and cynical people are less likely to try and change the world, whereas a lot of optimistic people are happier people, and optimistic people might be more likely to be crazy enough to think they can change the world.