Not at all. There are plenty of precedents where 1st worlders have received 6 figure salaries far above the market pay for the same job in the 1st world where there was economic turmoil. (Iraq right after the fall of Saddam.)

If you're working someplace remote, and you're not getting paid above market, then you're doing something wrong. (Hell, I've heard there are glorified clerks in remote places in the Aleutians that make near 6 figures for basically sitting around.) Given that some Mars colonists will be very rich, and that many governments and companies will pay you to do engineering and research there, Mars colonists are almost certain to have high salaries.