after tax pay of 75k a year isn't crazy unusual for software devs living in major cities. Living on 15k in these places is very doable, though some might consider it crazy depending on their habits.
After 6 years one could then live fairly well in a relatively poor country on 15k.
after tax pay of 75k a year isn't crazy unusual [...] in major cities
Less than half of that isn't crazy unusual everywhere else. Of course, anybody can just move there, and is qualified and lucky enough to find such a job.
Still doesn't change the OPs point, though; living on 15k/year is still a very convenient life.
Thus spake Eliezer:
It seems that many here might have outlandish ideas for ways of improving our lives. For instance, a recent post advocated installing really bright lights as a way to boost alertness and productivity. We should not adopt such hacks into our dogma until we're pretty sure they work; however, one way of knowing whether a crazy idea works is to try implementing it, and you may have more ideas than you're planning to implement.
So: please post all such lifehack ideas! Even if you haven't tried them, even if they seem unlikely to work. Post them separately, unless some other way would be more appropriate. If you've tried some idea and it hasn't worked, it would be useful to post that too.