The problem for me is that living normally in a dev job gives 15 total vacation/sick days a year.

One can surely take mini-retirements between jobs, but realistically, it's harder to get salary bumps when you NEED a job and you don't have the luxury of choosing to stay at your current spot if an offer isn't an increase. Also one normally needs to stay at jobs for two years or otherwise can look like a risky hire.

Five years of semi-monastic living with a good dev salary can be enough to buy freedom to work as little or as much as one chooses for the rest of life.