That's not my experience at all, thank goodness. I wouldn't have been playing D&D all these years either as a DM or as a player if that were true.
Engaging in an RPG with people who aren't enjoying it (or who don't care if I'm enjoying it) would be the worst way to spend four hours on a Saturday afternoon.
Not sure what you're getting at either I wasn't clear or you're misreading what I said... Hopefully everyone at the table is having fun. My point was that people playing PCs instead of DMing simply have a different focus. If I'm playing a PC I'm primarily concerned about my PC; I'm part of a team as well of course and making other people laugh is part of my schtick but my main concerns are about how my PC can help the team succeed. The DM has to think about how to make a world that's fun and engaging for everyone.