I can't find a good argument in favor of SF artists somehow being more worthy of that income than Chinese artists. You could use the same premise to segment in any other arbitrary manner and eg claim that older struggling artists are more worthy of that income than younger newer artists, and so on. How is it anything but a strictly subjective argument that will inherently vary from person to person as to what criteria is most important?
Fortunately what he's doing isn't exploiting, he's providing a valuable service in which the artists set their pricing and choose whether to accept the work. SF artists have no right to anything over an artist from an other city or country.
Try to read your comment changing the word artist by developer. Is your opinion still so strong? And don't forget that IT is one of the most abundant markets not a perpetually struggling one.
Fortunately what he's doing isn't exploiting, he's providing a valuable service in which the artists set their pricing and choose whether to accept the work. SF artists have no right to anything over an artist from an other city or country.