I'll try and keep it short with a bullet list, as I can tend to be long-winded about everything.
- Helped recover files on an old laptop in the Win XP days (how I got started).
- Breathed new life into older hardware that was too crappy for Windows.
- Thought it was neat, novel, fresh, etc.
- Free. Why pay for or pirate Windows?
- FOSS and, specifically, FOSS alternatives to paid software I'd otherwise have pirated.
- Less targeted for malware.
- Windows 11 says no to my aging, but plenty capable, computer (the last holdout on Windows til Win 10 hits EOL).
- Reasonable, optional telemetry.
- Not having to reboot (possibly more than once) during updates.
- Fun to learn.
There are some reasons to like Windows, but it's harder to justify with the direction Microsoft is, and has been, moving.
EDIT: To actually answer your question about Steam and Linux… because I have a Steam account that I've had for many, many years with 1000 games that predates me moving to Linux in a more serious capacity. While I could move to GOG (and have), I'm not just going to throw away my game library. But also, Steam working to make gaming more mainstream on Linux is a net positive for Linux in general. That was always the reason many people gave for why they wouldn't switch - that, and proprietary software that won't run on anything other than Windows or maybe Mac.
I went down that path about 2 years ago. Working from home and generally being a homebody, I'm basically on wifi all the time. I made the switch to Ting (from Sprint) and pay $15/mo, maybe $20 if I go over my 1GB data on 5G (I have alerts set up). It's not ideal if you drive a lot and stream music on Spotify or whatever (or if internet/power goes out), but if you literally have no life, don't go anywhere, and basically have nonstop wifi, Ting is pretty cool. It uses T-Mobile towers, so your mileage may vary. There's a few places it gets a little fucky, but it's been pretty reliable overall. I thought about looking into Mint recently, but decided not to even dive down that rabbit hole.