If you have a physist who is at the leading edge of their field you very much do want them teaching. How do you think you get the next generation of great physists?

It is similar to how when growing crops, like wheat, you should take the best of your harvest and use it for seed. Historically that is one of the most important and also one of the hardest things to teach farmers.

+ Many of the greats have loved teaching and benefited from the process. E.g. Richard Feynman, etc...