THIS. All the early retirees I know are either extremely rich (from their tech startups), or have a working spouse or immigrated abroad. No one has solved the riddle of healthcare costs while staying in the US post retirement on meagre income. This will especially hit hard when early retirees hit their late 40's / 50's, when health problems start kicking in but your resume starts looking rusty due to 15-20 years in retirement.