For me, it started as a general debugging process (as most bethesda games require). Then it turned into optimization for my shitty laptop. Then it became a how far can I push this process. Finally I started really enjoying the stories people were able to tell through mods.
As many have mentioned, someguy2000 is the man when it comes to fun story mods. The issue I've come across lately is finding a story that makes you feel something. kristakahashi's 3DNPC fallout bundle did it for me recently (specifically the story of Beep Boop).
All I know is that if it wasn't for modding I wouldn't have decided to go to school for computer science.
_________________“The worst thing that could possibly happen to anybody would be to not be used for anything by anybody. Thank you for using me, even though I didn't want to be used by anybody.” -Kurt Vonnegut