Instructor

Yes you can but it's fickle unless you have consistent conditions. it's seasonal so you'll need to do something else during the off season to keep afloat and you'll need to be willing to sacrifice a SIGNIFICANT amount of your riding time to work. This isn't so nice when the conditions aren't consistent, but if you get a decent blow for the majority of the week then it's not too bad and the job can be quite fun.

If you do a decent amount of hours in a week you can put away some good coin as well for what is a pretty chilled job. Just have to make sure you keep up to date with safety stuff and make sure you're not putting students in danger.

You've probably thought of this, you'd need to outlay for gear too.

I'm guessing a minimum $5k worth of gear to startup? Trainer kite, small kite, medium kite, large kite, two boards, a couple of different sized harnesses, impact vests, helments etc. You'd need to earn enough to pay off this gear as you go/save for the next lot of gear.

It seems to be a good supplement for guys with casual job hours outside kiting, shift workers etc.

work for a school. Learn the craft. Get GOOD qualifications and stick to a curriculum that is tried and true. You need more than 5 g's to set up a kite school....because one of the BIG factors is insurance. When you are an employee for a school the school pays the insurance and everyone is covered.
If you are youngish and unattached it is a great way to get to see other parts of the world while working on the beach. I might teach 6 hours in one day, but there is always two left for me at the end, usually when the wind is at it's strongest and not good for teaching.