The evidence just doesn't support this. There are analyses that purport to, but they look at wages rather than total compensation (including benefits)
[0] 2020-2021 prices from a previous employer's details
The internet, social media, higher living standards, globalization, etc. all of these things have moved people out of their local bubble and into a global worldview. It's much easier to be depressed when your expectations are 10x those of your parents or grandparents because you are now growing up in a more stable time and have more exposure to what is possible.
There will be exceptions but talk to older boomers or ideally the silent gen then talk to a recent college grad. I'm not playing "whose suffering is the greatest" or "greater suffering invalidates lesser suffering" but there is a massive difference in perspective and expectations.
I fall into the expectations trap myself and talking to older family members helps me get grounded, avoid doom-spiraling, and appreciate the freedom and opportunities that exist today.
Likewise, capital’s share of GDP is flat since the 1950s and if you factor out real estate, has declined from 25% to under 20%. https://www.brookings.edu/bpea-articles/deciphering-the-fall...
I would also posit that moving far away from grandma and not being forced to socialize with mixed-age communities at church had a much greater impact on ordinary people than whether capital has 20% or 25% share of GDP.
Ascribing the resulting unhappiness to departing from some sort of communal idyll where young people 'knew their place' is rather regressive I'd suggest.