I switched when my old Windoz XP install deflated in a blue screen of death. I didn’t even know there was a difference between an OS and the computer as a whole, but a friend gave me four live CDs with linux distros on them (Ubuntu 12.04, Bodhi, PClinus, can’t remember the fourth).
What made me stay was the FOSS ideals that make software available to all. I was so broke at the time that I didn’t have the money to buy a new $100 windows install. Without Linux I wouldn’t have had a computer. Since then it’s always been the ethos that has kept me with Linux. That being said, here are the unexpected benefits:
Entire file system is stored as text files. Super easy to back up ans administrate.
Support communities (Arch wiki, ubuntu forums, etc…) are filled with highly educated members who have very often asked and answered the questions I had.
The app repositories. It blew my mind when I found out I didn’t have to hunt around on the web for an .exe file that might be coming from an insecure source. Linux apps (distro repos, flatpaks, snaps) are centrally available from your terminal just for your distribution.
Lastly a more overarching meta-point, the software respects thr user. Windows and MacOS don’t respect you and make it difficult to maintain freedom in the way that you use your computer and manage your files.