Highest income of English teacher you ever know?

I saw this claim in other sub that he knows an English teacher in one of Shanghai's top school can rake in over 1 million yuan a year for all the tutoring work in & out of school, while being under 30, and it's a piece of cake.

I don't know much about English teaching but it sounds quite unrealistic. For one, my vague idea of this profession gives me the impresssion that, even the highest paid Caucasian teachers from anglophone countries with authentic degree ineducation can hardly earn more than half a million.

And two, English is not that hard or important in secondary education, compared to physics or math, hence a smaller market. And three, it's hard to believe that families which can afford such obscenely priced teachers/tutors would be in such bad a situation that their kids need to pay so much for scores. Rich kids usually travel a lot and speak more than one foreign language from a very early stage.