Other thread prompted me to wonder something. Pretty self-explanatory poll.
For some types of campaign I only want to be DM in our current group (e.g. greyhawk/DS/Ravenloft) , for others I prefer to be a player (FR,Eberron). That is because I use mostly old official stuff (partially modded heavily and converted to 5e), but others in my group did buy the 5e stuff.
I got profound background knowledge on several campaign worlds, on some so much, that I would often have no fun as a player.