"Hey, is there good money in teaching drums? I think I might get into it for some extra cash."
Do not get into teaching out of the desparation for money!
Why?
There is a clear difference between teachers who teach for the passion of teaching and their craft versus those teaching out of necessity, or a "teacher" who is trying to generate income between gigs.
Teaching requires patience, care, support, empathy and flexibility.
When you don't possess the aforementioned traits and you're in it merely for "extra cash" you likely won't last. This is because your goal is making money, whereas your goal should be doing whatever it takes to get that student to their next level.
A teacher should be able to build rapport, motivate, inspire, engage and help meet the goals and desires of the student in addition to developing the weaknesses of the student from the teacher's perspective.
When a student asks for drum lessons from a teacher they are seeking help and teachers should be coming from the genuine angle of providing a service aiming to help the student overcome any challenges or shortcomings they have.