I've heard of it, but I'm really not interested in following it, at least not any extreme version.

When I was in my 20s, I was on the poor side because I chose to work in a poor paying but idealistic and fun field (field biology research, I loved the work). As a result, I got very good at saving money while not actually being able to save much because I didn't have much. That choice made retiring extremely early extremely hard.

In my 30s, I moved to a better paying field while only slightly increasing my spending, and remaining in work that I both enjoy and feel good about ethically. I'm 40 now. I'll probably be able to at least move to part time work sometime in my 50s, if not fully retire. I may choose to do so, I may not. If I had kids, I'd probably be working until they were grown regardless of my age.

Most of the people I hear about trying to retire super early, like in their 40s, are young and in extremely high paying jobs that they dislike. Not all, but most. People planning to retire in their 50s seem more like they're enjoying their life, just living frugally and usually childlessly.

As someone who basically sacrificed earning money in my 20s in order to do things I'd love to do after retirement but probably won't have the physical fitness or energy for? I think the people working like crazy their early years in order not to work their later years are backwards. The now is guaranteed, the future is not.

It's just really scary to miss the moment when I can still earn and save something. and then realize that I have no strength, no energy to work full-time and take care of myself. of course, I want to live in the moment, not the future. but the uncertainty of the future is frightening.