All these topics are so advanced that even for someone trained in one it would take years to become proficient in the other.

Source: I'm a Physics PhD

Fun fact: When I was in a highly respected grad school in the 1980s (multiple Nobel Prize winners in the department), the QFT course was presented in such an obscure way, I stopped attending lectures, and I doubt anyone passed. The next year under "QFT" they taught Ashcroft -- i.e. a Solid State Physics course. That way requirements were met.

I took QFT in college and then grad school in two of the leading institutions in HEP. I can’t say the instruction was very enlightening in either place. Whichever path you take (not sure what you had in the 80s, I’m thinking of Peskin & Schroeder / Schwartz / Weinberg, maybe even supposedly easier textbooks like Nutshell) it’s just a very dense subject.

Now, GR or at least the core of it is a lot easier as long as you’re mathematically prepared for differential geometry.

Btw, I took particle physics from the Peskin in Peskin & Schroeder when I was an undergrad. Everyone in the class (like four of us by the third week?) was super duper lost by midterm.

yeah like this for anything. String theory is easy if you're mathematically prepared by being a field's medalist

Having attended many IAS talks, I don’t think string theory is easy for the likes of Ed Witten.

0.001% is already about 800_000 people :-)

80,000. And imagine, QFT is even harder than percentages!

I wonder how many people on earth can compute 8_000_000_000 * 0.001% 'cos obviously I'm not in that part :-)