Most people do not wear tungsten wedding rings. A wedding band can be resized and it's typical to have it resized several times during a long marriage. This is a legitimate downside of smart rings that is only shared with one niche-but-overrepresented-here option.
The advantage of my tungsten wedding ring is I have 5 of them, some in different sizes, and it cost me less than $100 for them.
Since this is HN: About 25% of US males wear a tungsten wedding band. So, not most, but a sizable amount.
smart rings aren't meant to last more than a couple years though - the rate of progress on these means that you're more likely going to be paying for a smart ring subscription than a physical object
Mine is serinium (a zirconium/titanium/nickel/etc. alloy), because it was cheap (because I was poor and wanted to spend more money on my then-fiancée's, of course). Serinium rings are also not resizable, and, from what I understand, they are becoming more popular (because they are cheap).
Cobalt Chrome ring wearer here (and my wife). Not so niche I guess
Odd, I was married for almost twenty years during which I think I took off my ring twice (maybe not even that much—if I recall correctly, I persuaded the surgical staff to tape my ring rather than have me remove it when I had surgery). Never had to resize it and it fit fine the whole time. I don’t know what lifestyle leads to a finger changing size dramatically during the lifespan of a smart ring.
My experience with devices with very small batteries is that they lose capacity (below 80%) quickly after a couple of years of daily use. By the time you need the ring resized, the battery might be worn out anyway.
It’s in reality a disposable product unfortunately, unlike a wedding band.