I have things that I can confidently call conworlds going back to my middle school days in the late 90s.

My current Lonely Galaxy setting is a rework of an earlier project I called variously The Last Grand Adventure or En after the in-universe name of the world. It has roots going back to my freshman year of college in the early 2000s.

I conworld mainly as a means of escapism. My current conworld was born out of a time of extreme stress. I couldn’t handle the real world, so I retreated into my own. Perhaps not the most healthy way to cope, but eh.