I have known people to be content with what they have, but life is a little more complicated than just being content with what they have, certainly these days. It's not just about things though, it's about who a person is, how they develop and grow emotionally and how they learn about life, themselves and others. All of this requires effort, and getting outside the comfortable places they self-limit to.
Some are incapable of change, but those people would never read a post like this to the end; they'd give up.