For me it was pretty gradual. In my university research a couple years ago I needed to work with the university's supercomputer running RHEL, so I got some exposure there. At some point I put Mint on my laptop, keeping Windows on my desktop "in case I needed to do any real work", then about a year ago I put linux* on my desktop as well. I do still have a Windows dual-boot just in case there's some weird software I need to use, but I haven't touched it more than once or twice since. I switched partially out of curiosity, but largely as part of an effort to de-google and de-microsoft my stuff so I'm more in control.

*distro-hopped a bit, but now am settled on EndeavourOS

I was surprised at how much you needed the terminal, but also how easy it was to use the terminal after a bit of practice. I prefer it to GUIs for a lot of things now (like git). Also, installing software from a package manager rather than going to a website and downloading it. I didn't like that at first, but I love that concept so much more now, since I can just sudo apt upgrade and everything is up-to-date (no downloading the new version after an update).

I'm now to the point that when I do need to use a windows machine for some reason, it takes me a second to remember how things work. It's kinda a weird feeling tbh haha