> The hedonic treadmill is referring to the fact that, when a problem is solved, the level of pleasure or happiness individuals experience reportedly quickly returns to the pre-solution baseline.

That is not a fact or objective truth or even historical, that is a hypothesis and a theory.

And the distinction matters. It is not in fact true that all people in all setups and classes and historical periods and periods of their lives were equally happy. In fact, you can be unhappy, solve the problem and be more happy/content for the rest of your life. Overall peoples happiness go up and down.

Hedonistic treadmill is a theory. It is also a slight of hand argumentative trick to shoo away valid complains people have. It was worst in the past, but you are not completely happy accepting bullshit today, therefore you just dont know how good you have it, basically.

Global warming make quite a lot of people (like hundred thousands) miserable as they had to evacuate and then return back to non-existent houses. They literally lost everything except bank account and whatever fit into the car. The areas with high drug and alcohol use, high violence rates are in fact not full of people who have it too good. I could go on ... the inequality and accumulation of power is threatening to make most of us all worst off and it is not because we got spoiled by hedonistic treadmill.