If you're down here with us stupids you can spend a lot of time on it, you'll get some insight into the basics, but you won't be good at it - certainly not good enough to do it for a living.

Yes, GR is taught at undergrad level. But that doesn't mean most undergrads really understand it, or can do much with it beyond solve a few toy exam problems. Because undergrad GR and QM are introductory courses for beginners.

It takes a PhD to start acquiring fluency, and that's years of constant grind doing nothing else but. It's also hugely helpful to have mentors and/or parents and/or other family members who can give personal help.