Why Is Everybody Lifting Weights All of a Sudden: Some Guesses

I have a vague impression that people in my various social circles are taking up serious weight lifting as a hobby and life practice. In particular, a) nerds and b) leftists seem to be getting into it in greater numbers. If I were doing a piece of Professional Journalism here, I would make some half-hearted effort at anchoring my vague feeling in an empirical fact or two, but this is just my substack, so instead I can handwave that and then go on to make some observations and guesses based on my own recent experiences in the gym.