I think happiness is very orthogonal to economic progress. It's a uniquely American myth to believe that GDP growth is a proxy for the happiness of a nation's people. (We export it all over the place).
Social systems which do not provide economic growth have been systematically destroyed over the past few generations. Workers have to be mobile to compete; public spaces have been eroded to favor the privately owned; placement into employment has shifted from personal connection to faceless, autonomous, nationwide filtering; geography of public spaces favors the individual over the group (again, to eliminate sharing of resources); media and culture is far more national or even global, rather than local; religion and all of its communal benefits (and downsides!) is waning...
Some of these systems benefit social cohesion and happiness a lot. Often at the expense of individual liberty, that's why it's easy for Americans to rationalize shedding them.
I don't think it's a grand conspiracy, but it seems obvious to me that this cultural shift is occurring because of the dominance of economic life over all other forms. Unfortunately, economic growth is power, and therefore once one party has it, everyone else must shift to compete. We are seeing this reorganization at every scale, from the individual, to the corporate, to the national, up to the global scale. It isn't even close to being over.
I think millenials/genZ realize that our culture is missing something, but they can't quite articulate what it is. This is because the entire discussion folds into this worldview. Look at how many of us are discussing the price of this or the price of that in this thread!