I believe it's possible to achieve the same level of life satisfaction by translating your experience of the world through a lens of gratitude and purpose. I've had opportunities to meet and get to know people with high net worth (mostly successful entrepreneurs) and people that willingly chose to live below the poverty line (religious devotees, teachers in poor communities, public advocates in poorly-funded non-profits, etc). I can't say one is happier than the other. Both require you to sacrifice things you might otherwise want. For the rich, that sacrifice usually takes the form of unstable family life (if any family at all) and alienated relationships with children because they work too much. For the poor, that takes the form of more immediate, material sacrifices like worrying about food, healthcare, and housing. But something both share in common is that they can be happy if they are grateful for what they have. Gratitude is a powerful thing.
Curiously enough, the least happy people I've met are the ones that fall into neither category. Enough money to feel safe, fed, and warm, but no direction or meaning in their life. They aren't sure what to do with themselves. Should they try for more money? Should they choose a less vapid career path? They can't give up the middle-class salary or the middle-class experience. It's very sad.