> education is an investment in human capital.

This is not universally true. At least, not all education leads to the same increase in human capital.

I would argue that getting educated about art history does nothing to increase human capital. You may have enjoyed learning about art history, but knowing what a tryptic is does not make you a more productive member of society.

And the fact that art history majors earn a lot less than stem majors on average seems to confirm this. Being able to build bridges is simply more valuable to society than knowing some obscure facts about dead people.