I’m curious about your theory too. I have a couple of possibilities:
1) returning Vietnam veterans who couldn’t find work, or were unable to hold a job as a result of their PTSD or other problems.
2) Too many college graduates (who had attended college rather than being in Vietnam) and not enough jobs for art history majors, no work.
3) Reagan’s presidency and the dissolution of the social safety net that had been around since Johnson and the Great Society.
4) The release of the various Star Wars movies that moved American thinking from the profound to the world of fantasy.
5) The creation and completion of the Interstate Highway system that made it easier for people to evade responsibility, move from place to place, and never have to work.