Happiness is a tricky thing. Not only being happy, but also measuring happiness. Robert Frank has an essay about money and happiness, How not to buy happiness. His basically says that yes you can buy happiness, but don't go spending money on large cars, houses & more stuff, but you can make your life better by reducing your commute, spend more time with friends and travel more. Yes, those things cost money too, if usually not directly.
The other thing from the article is that it seems from statistics that people on average don't feel more happy when a society becomes richer or when they live in a richer society, but they do feel happier when they become more rich relatively to the society they live in.
Now, this can be understood in two ways. Either the meaning of happiness changes when people become richer and happier, i.e. people in richer countries are happier than in poorer countries, or people are really always equally happy in whatever country, but if they think they're richer than average it makes them feel more happy.
But if people would really prefer being richer than their neighbour to being absolutely richer, it would follow that they would prefer to move to poorer countries (assuming they could take their riches with them). They seem to do that only seldom and only for the reason that the weather or the exchange rate is benign. In fact people poor people that are relatively well off in their own country, seem to be happy on average to move to richer countries where they would be relatively poor and absolutely rich. So it has to be the first way.