I've known a few rich people who seem happy, but deep down wish they never had the responsibilities.
"Poor" can be defined as having nothing at all, to having the basic necessities.
I'd define myself as poor, but I keep my head afloat, and have food, clothing and shelter, and I'm quite content. See, if one can find happiness minus wealth, they're truly happy. If a wealthy person loses their wealth, they'll never know what it means to be happy without it.