Sorry disagree with the subject line here, who is defining what is realistic and unrealistic in terms of salary. Considering averages doesn't make sense. It is important to know the ranges yes, but beyond that each individual should try to stay updated with their market value, talk to recruiters get offers, understand what is the budget for your skill (whether or not you are planning to shift your job).
Just going by averages will make you underpaid soon (if not already).
Regarding the salaries posted on the other threads i personally know folks getting paid those amounts or even more :), so they are not far fetched as such.