I originally had really long answers to these questions, but I tried to trim my answers to their fundamentals.
I originally planned to be a professor, which is the only profession that can use string theory. More recently I’ve decided that I almost certainly don’t want to do this, because I don’t think I could be a professor and also keep my integrity: Professor salaries come from student tuition and government grants, both of which are scam-like.
In approximate order of importance
- I am ambitious and I want to do something groundbreaking, but I no longer think it’s possible to do anything truly important in my field.
- It’s a lot of work, which conflicts with other interests that I have. Much of it is soul-draining busywork too, and no matter how much work you’re doing, you aren’t doing nearly enough work to get the ~1 desirable tenure-track professorship that opens up in the world every year.
- The salary (especially for PhD students) is extremely low.
If I had a clear answer to that question, I would just do it.