If you receive low wages in the private sector, it might be an indication that you're not providing much value, and that your time and effort are probably better spent in some other endeavour. It could also be an indication of some artificial or temporary misallocation of resources. The same goes for high wages. You could be providing genuine value, or your profit could be due to some intervention or other.
In the meantime, people who can't make a living doing teaching shouldn't teach. Or they shouldn't do it as their day job. At the very least, they shouldn't demand other people subsidize their choices.