it's an MMORPG. if you don't understand why people want to progress their character, then there is not much to tell you....
now there is something I don't understand: why do you even care about it? just focus on your chars, your guild, M+ group or whatever the F you do in this game, I don't care about it, it doesn't matter to me or my chars progress. so why would you care about what I'm doing in this game? am I stealing gear from you?