I'm in this camp (as are a lot of people outside of this forum). The Blue Zones books suggest pretty strongly that the communities where folks live the longest, healthiest, and happiest lives aren't filled with early retirees, but with folks who stay active and connected to others on a daily basis. In particular, they identify a sense of purpose, good eating habits, natural exercise, and social interactions as the four pillars. The fact that there are so many threads in the pre- and post-RE subforums about what to do when retired, whether to return to work, how to make friends, and so on only reinforces these findings. People here instinctively get this on some level, even if they would never directly say that the reason they're so desperate to find hobbies and friends when retired is because they'd naturally turn into depressed hermits if they didn't have to show up to work on a daily basis.
A number of other studies have also suggested that the risk of death rises sharply after retirement, and that early retirees tend to die sooner than traditional retirees. Some of this is ostensibly related to health concerns that force some folks into early retirement, but I definitely feel the lack of purpose that comes from leaving a job and the social connections most people establish within them are at least as large of a factor, if not the dominant factor. The Okinawans call it ikigai; the Nicoyans call it a plan de vida. To put it simply, you need a reason to get up in the morning, and you need to feel connected to people on some level (or as Freud called it, work and love). Retirement, early or otherwise, doesn't necessarily give you either of these things, although you can find or maintain these things in RE, just as you can in R. However, you can also find it through work.
Personally, if we had enough money right now to convince DW we could RE (I'm guessing this would be at least 2.25M...1M for four college funds and 1.25M for 50k in dividends), I'm pretty sure I wouldn't RE, at least unless I were going into a different career path (at which point I wouldn't be RE). I'm a preschool teacher, and I get the purpose in droves from working with my kids and the socialization from interacting with coworkers, even though there's an endless amount of administrative nonsense to deal with. I'm pretty sure DW would want to start some kind of small sustainable business involving children, education, and homesteading, so I could hop to that for purpose and such. But my point is that I wouldn't automatically jump ship. I'm a very strong introvert, and I know I'd want to spend all day when not with DW or the kids listening to music and surfing the Internet, and that wouldn't be the best thing for me to do, though I'd thoroughly enjoy it.
