For me it’s the sense of progression. I cognitively know it’s meaningless progression but emotionally I still feel value out of that artificial progression. Like I’ve achieved something. In addition to that it’s freeing in that it’s the most objectively fair setting(I suppose this is less true in modern games than it used to be sadly) in a game it doesn’t matter who you are or what your reality is, it doesn’t exist there. No problems from your real life have to exist there so that escapism can be a very addictive coping mechanism.