It does seem appealing to compress it into a few years, doesn't it.
But I don't think it works for me at this point. First, the math. I believe 20k gross is ~10k after tax where I live. My absolute minimum acceptable lifestyle costs 30k/year. Which leaves the possibility of saving 90k/year. So I get three free years for every year worked. Brings to mind the Ciolkowski equation.
Three years for every year worked, neglecting investments, but also opportunity cost, and the fact that I absolutely detest working for others and even a year of working full-time is a dreadful prospect to me.
Assuming life expectancy of 85 and no state pension, I would need to work full-time for about 13 years, no time-off, optimistically assuming no mental breakdown from all that work. So I end up at 45, possibly bald, with no savings except to fund what I considered the minimum acceptable lifestyle at 32. That is not good.
The opportunity cost. I now work for about 2-3 months / year (and benefit from lower tax at lower income), building a quite possibly successful business venture on the side, and devoting lots and lots of time to my hobbies.
Aging. I would not want to sacrfice a year of my 30s for three years of my 50s.