I think it's a fun distraction from my problems and responsibilities to put the time in molding or expanding fictional universes and characters, both original and canon ones.

Also very relaxing, when I'm agitated for some reason, theorizing, exploring concepts, or imagining characters in x situations is a nice head brake when I can't get myself to simply not think about things.

Now, without them I probably would just have a different coping material/hobby, just not sure what. I wonder if it would be a more or less important one.