Why are some people chronically unhappy?

Why are some people chronically unhappy?

Adriana Robakowski (Cheerleader) gives expert video advice on: Is happiness worth pursuing?; What are the essential ingredients of happiness?; What elements interfere with happiness? and more...

I guess that some people are Unhappy because they've been going through stuff. I know a few people who have been going through that, and I guess they're Unhappy because they can't realize that some people have so much less than them, so when they seem like they might have nothing, but they really are way more lucky than a lot of people.