I suppose for developers you flip it right.

"Normal SV developers spend 4 to 5 hours a night coding on personal projects"

The normal people watching their TV would think those devs spend a ridiculous amount of time coding.

If you spend 4-5 hours a night coding on personal projects you probably have both a pretty strong self image of yourself as a developer and probably people who know you see you that way as well. Same goes for if you read for 4-5 hours a night, gamed, worked out, cooked, swam, whatever. Reader, gamer, bodybuilder, amateur chef, swimmer, etc. If you consistently do something for 4-5 hours a night it's generally a big part of who you are.

TV stands alone where people do it 4-5 hours a night and its not considered being super in to that thing. People in the tv watching category don't see it as choosing to do a thing. It's just part of what you do. Sleep, work, then tv. Repeat. They don't identify as a tv watcher any more than they do as a sleeper.

What'd the people who just turn their mind off _do_ before TV.

Sit around and shoot the shit with friends and family.

Form mobs and look for people to hang.