I love me some online coop, especially with friends. I even enjoy a few fighting games, like Tekken, although those are also more fun with friends.

Single player is pretty fun though, especially ones that are intended to be single player but have the option to do multiplayer like Valhiem and BG3.

I think it mostly comes down to how competitive people want to be. A lot of younger folks, including me 20 years ago, loved seeing ourselves on leaderboards even in team games. But over time the experience of getting immersed in single player or laughing about a shared experience in coop is just more fun that reminiscing about being at the top of a counterstrike match 15 years ago.

Plus some of us remember when skins and new maps were added to many games by the devs or through mods well before microtransactions became popular.