Downward mobility is almost entirely caused by housing costs, which are a self-inflicted problem. We don't, as a matter of intentional policy, build enough housing. I live in an expensive area and I'm always shocked by how many of my friends who cannot afford to buy a home (or even a condo) are NIMBYs. These are people in their 20s through 40s who have been earning since college, can't afford to buy, yet get annoyed…
Are they actually NIMBYs or just annoyed? I live in a major metro downtown full of construction and fully support it 100%, but that doesn't mean it doesn't irritate me. Roads and sidewalks are constantly randomly closing. Every bridge across the local highway is currently closed for the next five years. My wife had every tire on a brand new go flat within three months because of nails on the roads. Our houses are all covered in yellow dust because the gas company dug up bedrock 9 years ago, left an enormous pile on a street corner, which then washed away in rain and still covers half the sidewalks nearly a decade later. Most of the housing ends up becoming short-term rentals, which in turn mostly become party houses, so the streets are strewn with broken liquor bottles all the time, cops are getting called in the middle of the night to break up fights with strippers. My car's hatch got destroyed by a city dump truck a few years back and I've been hit while parked two other times by work trucks. All of my power tools were stolen out of my garage by a work crew because the original builders put me on the same radio channel as the guy two doors down, so my garage randomly opened without me knowing about it.
I still support it. We need all the housing we can get. But I do get endlessly irritated by the attitude on Hacker News that no person could ever oppose rebuilding a neighborhood while people still live in it for a good reason and they must all by miserly hoarders trying to pull the ladder up from beneath them.