In the "casual" instructing environment, it is very much up to the individual how much they earn. For an instructor who does the right thing by their students and gains a good reputation, 40K is not far off the mark. Some of my instructors take home a lot more than I do and yes, I own the school!
An instructor rating doesn't mean that GA owes you a living. (whatever you may be told when you sign up for the instructor course!)
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