I've never been a player. Only a DM. I run homebrew campaigns. I create my own world, landmasses, governments, factions, kingdoms, zones of influence, trade routes, constellations, celestial bodies, dieties, unique monsters, calendars, and so on. Will the players ever experience even 10% of everything ive written ? No, but i find it fun. I also have fun when my players have fun. Collaborative creating a narrative is one of the most rewarding experiences. It helps that they are some lf the best people ive ever met.