2 of the reasons here are legit. I absolutely understand the possible regret and people treating you like a misfit. Fortunately for the second point, there are

2 of the reasons here are legit. I absolutely understand the possible regret and people treating you like a misfit. Fortunately for the second point, there are communities of people doing the same thing that you can join in and be apart of a community. The other three are generally seen as the downsides of FIRE and something adherents talk a lot about. If you don't build the life you want before you retire, you will be bored. If you don't sacrifice your life, hobbies and building up a solid life outside of work, you won't be bored. Instead you will retire and have things to do in retire. If you base your happiness off retiring rather than hobbies and a social circle, you will be miserable. Overall, this is common with FIRE. People work their ass off to retire early not thinking about what is next. If you think about it, put some effort into developing hobbies, a social circle, and base your happiness off that, you will do just fine.