There was no special reason for switching 25 years ago. A friend of mine used Debian and I tried it out. Not being a gamer must have helped because if you like playing, chances to encounter a game that only runs on Windows are quite high.
Now the reason why I never changed back. Once the system runs, which may take some rime depending on how customized you want it, it always runs the same way. I never had a slowing down due to updates. Another reason may be not having to think about viruses or malware. Never had it and most likely never will. Antivirus? They may exist for Linux but I have never used them.
In a few words. It just works.