I guess you are in math or physics. You said,
但是如果仅仅副教授,收入上实在是见不得人。
I don't know how much income you are expecting, but if you go to Wall Street and work for 2 years, it's very realistic to save $100,000. After that you can invest it and the interest should cover the salary difference between a professor and a associate professor. Problem solved! You do have to work for two more years here but it's going to be a good experience too.