OP - I read the article you linked, and Dan Buettner made a common mistake (one that skyhigh, the uber-troll of this sub-forum that others have mentioned) in incorrectly conflating two ideas. Those concepts are "retirement" and a bundle of things like lack of meaning, reduced social network, and lack of physical activity. Here's one example from the article, where he demonstrates the error in thinking:
“Did you ever think about that word ‘retirement’?” Buettner asked the audience. “It is that artificial punctuation that means the end of your productive life and the beginning of your life of repose. And there is a very dangerous mortality spike that year — 11,000 extra people die the year they retire.”
In his view, retirement "means the end of your productive life and the beginning of your life of repose". Well, yeah! If you think of retirement as an end and stop there they I can definitely see his argument. And it's true that in the general public this idea is all too common. However, if you read the MMM blog or you spend time on these forums you'll see that the vast, vast majority of people
here don't accept the idea that retirement, especially early retirement, is
just an end. For most people here it is also a beginning. Speaking only for myself, here are some of the beginnings I've had since FIRE 5.5 years ago:
I started to volunteer with the local symphony. I am one of the public faces of the organization at events doing things like answering questions about season tickets and other ticket packages, providing information about upcoming events, information about the artist, and doing office work to free up the employees to do more fulfilling work that they're more qualified than I am to do. I also drive visiting artists, often world-renowned, to various activities. I just had a fantastic one-on-one conversation with a concert pianist I was driving to the airport about how he approaches his performance after flying in to perform a challenging concerto with a symphony orchestra and conductor he's never met. That made my week!
I volunteer as a math tutor. Just last night - literally 16 hours ago - I worked with a girl who got a 0% score on a math test. After an hour of working with her she literally ran to her mom with the paper we'd been working on yelling, "look mom - I can do it now!". That is a bajillion times more satisfying than my best day at work, and I really liked my career.
5 years after starting as a total beginner, I finally was able to play Chopin's Nocturne in C# Minor, Op. Posth.
I was available to help my mom recover from a hip replacement.
I could go on and on and on, but you get the point.
After reading this forum for a decade, I can say with certainty that while the particular things I'm doing are unique, my approach to early retirement is not. Some people here talk about retiring TO something rather than FROM something. While I dislike that phrasing because I definitely retired from my job without any idea of the cool things I'd get to do, I did know that the same attributes that allowed me to retire at 42 would enable me to create a fulfilling retirement. The reality of that has been better than I could have imagined.
So yes, retirement can lead to the negatives you point to, but if you look around the blog and the forum you'll see we have a community of people here who are actively building a concept of retirement that supports a healthy, positive retirement that leads to healthier and happier people.