I think group theory is both very useful and interesting. There’s no need to get into Galois theory but the basics are definitely applicable in everyday life.

I think group theory is both very useful and interesting. There’s no need to get into Galois theory but the basics are definitely applicable in everyday life. I agree there are tons of other things that people should study, like basic linguistics, relativity, quantum physics, optics etc. Geometry should be on top of the list, for as Plato said “let no one ignorant of geometry enter”. But I don’t think time is an issue really, if you just spend an hour or so each evening reading you csn quickly get a basic understanding of lots of topics in not thst many years.