Your supposed connection of country-level economic situation and happiness reminds me of this great comment:

"I can't stand the conflation of "satisfied" and "happy." It's insane. There is more happiness in one Zimbabwean (country "happiness" rank: 143) than in one hundred Icelanders (country "happiness" rank: 2, worldwide antidepressant consumption rank: 1.) Go stand in a crowd of people and count the fucking smiles and the fucking laughter.

"It is all part of this broader wave of newspeak. If you can quite literally redefine happiness, you can redefine anything. Nothing has meaning anymore. You will live alone, you will consume antidepressants, you will be protected from the sunlight, you will not smile, you will not laugh, and you will be happy." [0]

[0] https://news.ycombinator.com/item?id=46295573

Hmmmm maybe economic success removes discomforts which removes unhappiness but this means that moments of happiness don't feel as good compared to the baseline. Like, people in rich countries are more stably content, while people in poor countries have more emotional variance over time.