what is useful? Did I use my knowledge of polaritons when working for an insurance company? Perhaps the details of etching -OH terminated diamond under esem helped me when I was maintaining servers, no no it must have been linear alg that enabled me to tutor kids in ochem.

like my degree hasn't helped me to much explicitly, but it was fun. sometimes answering peoples' questions about physics is fulfilling to them, and the act of learning crap helped fill me out (including realising how utterly naive I was at assuming scientific knowledge was more valueable than other kinds).

You see a problem in our society: that we only reward a very narrow subset of kinds of labour and grossly unevenly at that and you blame people for studying something that interested them. Why? Would we be better off if they were buying up apartments and renting them to an underclass? that's something that pays highly. Maybe we need more gunsmiths! afterall inventing the machine gun reduced death and destruction during war. Perhaps instead they should have studied finance, because we have far too few insurance brokers?