In Cancun, we have some of the highest and lowest paid instructors in the world
$300-$10,000 USD per month. The difference is sales abilities and languages. the average is between $2000-$4000 USD. Which is perfectly acceptable to live of down here, you pay minimal income tax (2-10%) and you can get a 2 bedroom apartment for $300. You do the math. Will you get immensly ritch teaching diving, probably not, but most instructors dont do it for that, it is a lifestyle thing. Most instructors do it for the love and adventure of it, especially as a way to travel and live overseas while young and free.
If I was to dream of the perfect dive job, it would be teaching super VIP's on a freelance basis. Use their pool, their yacht in the french riviera, their gulfstream to get there, include a full set of top of the line custom selected dive gear to their taste and requirement, and charge them $5000 USD per course. They spend that much on a night in the Ritz Carlton anyway, and that doesnt include the minibar.
Look for companies in Vegas, European and industry royalty, be available anywhere, anytime 24/7. How hard would you have to work??