I almost never buy multiplayer-focused games anymore. Of course not all gamers are shitty, but enough are to matter. Having left those games behind I can see how they were taking more joy from my life than they added. If friends want to do private co-op that's cool, but it's also rarer now that we're all older.

As far as sales go, I love playing a year or two behind new releases. Patched games at a discount ftw and timing doesn't matter in single-player games.