I discovered today that my most played game on Steam is Astronner with about 500 hours, and my second most played is Surviving Mars with about 500 hours.
Diablo 2 from launch, I won't even guess the hours because it's over 10k easy and that's just not good. Path of Exile says 4k+ hours as well. I'm an old fart though.
It's probably the same for me. I played, quit, and restarted Diablo II so many times since middle school. It just has a replayability factor after you've been away from a few years.