They don't have to sell their bodies to make a decent living. They sell their bodies so they can enjoy a luxurious existence with minimal effort. The Chinese are particularly susceptible because of their materialistic lifestyle and lack of morals.
I agree. Go to any major cities in western countries with a large Chinese (commonly referred to as Asians) population and there's also a vibrant commercial sex industry. Where there's a high demand for prostitutes from Asian men, there will always be a large supply of Asian prostitutes supplied by the triads.
Unfortunately cities like San Francisco, Vancouver, Sydney and Melbourne are more like Asian cities instead of Western cities.
It is not how much one can earn rather than the choice they made to sell their bodies for cash. There are other ways to earn a living. Why they chose prostitution is because they like both sex and money or would rather have sex for a living than do dishes or cook and rather be paid for sex than giving sex to guys for the mere pleasure of it.