Materially life sucked; but less shit to worry about, and you had the stuff that mattered: relationships. Couldn't get anywhere in that sort of world without them -- so everyone made an effort to cultivate friends, or atleast many acquaintances.
Now? You don't need friends -- you have money. Neither are you willing to suffer through another's perceived faults. Everyone is quick to turn others into persona non gratas because of silly things like political views, or a certain character quirk that drives the neurotic insane, or the way they dress, speak, or act.
Doesn't help that it starts at the familial level. If your family isn't large or your family hasn't made the effort to cultivate relationships, then you're less likely to be exposed to other people, and build your own from there. +1 to how most American families are tiny, and most aren't intimate with their extended family. No one knows how to get along with other people. Everyone has to be a perfect piece of furniture to be allowed a place in the dining room of one's life.
And who has the time? There's so much shit to do. Gotta spend all my free time building up my career. My neighbours? Why would I waste a perfectly good evening drinking and talking about life, when I could go to my company's happy hour to schmooze with my colleagues... or better yet: get a good night's rest so I can give my 100% to my company's: shareholders/c-suite/founders/whatever. My neighbours aren't gonna get me that promotion -- so fuck em.
Shit, my house needs renovations. I gotta bring my kids to piano recital. I gotta get a repair man for the washer. I gotta buy new clothes, because my old ones are starting to fall apart. I gotta bring my car for maintenance. I gotta watch entertainment because I'm so fucking exhausted from selling my mind for the privilege of being able to stay alive. Gotta set up a doctor's appointment because I got RSI in my hands. Gotta call up my insurance company because they denied another fucking claim.
Material prosperity is a pox on the human soul.