Comment by cratermoon

I tried that. I washed out after one year, because I couldn't sustain the laser-focused interest on the single area I was supposed to be studying in grad school. At an entire large state university of tens of thousands of students and classes on every subject, I was only supposed to take ones the advisors deemed "in my field".

There might be universities out there with "a la carte" grad programs, but I'm not aware of any.