As I get older, I get more scared of what I can lose, and of dying - I don't feel immortal as I did in my 20s. Maybe that's part of the territorry when you become a parent?
I'm more conscious and aware of how my quality of life is now. And I agree, it's easier to appreciate what you have when you have very little. But it's also really soul destroying being poor. I have had long periods of worrying about hot to pay the bills and food, and it's still deep in me, although I am fine now (not rich at all, but at least not struggling anymore).
I feel more grounded now. And "being happy" is something I have to remember that I am, deep down, even when things are difficult.
You might enjoy some of the articles:
markmanson.net/best-articles