Hmmm. I'm seeing these in many EDC pocket dumps.
I just don't get the appeal.

Maybe I'm just getting old but I am baffled as well.

I only learned of them in the last month or so. Some of them look pretty neat. I'm working on learning how to fidget, so I can have an excuse to get one! I wouldn't carry it around with me though. It would sit on my desk to help me get through the long boring work conference phone calls.

That's what ETS is for .

Being mission oriented, I'm holding out for a tactical, glow-in-the-dark titanium spinner ... so I can figdet with a mission.

Some designs are useful multi-purpose tools:
https://www.youtube.com/watch?v=VlVRB3BoWOU
Jörg also mentions an application in the medical sector (ADHS).
They may also serve as bearing for a bow drill.

No idea what you are talking about...

Some look like they'd be useful as bearing block for a bow drill set.

Edit: Ah someone brought this up already

My son's friend has something like one of these. Apparently Costco sells a 5 pack, so you can have multiple redundancies.

https://www.amazon.ca/s/?ie=UTF8&key...sl_7b2dtkg66n_e

...I'd rather carry something useful. Cell battery, notebook, business cards, lighter...