New player

Hello everyone.I started playing this game again after a break of several years and i found many new things and couldnt find anyone to explain them to me.I managed to understand some aspects of the game but i still have one question to ask: how do most of the players do damage that high?i mean its beyond the stats or the gear.What special stones do they use to crit 40-50k or even 100-200.I tried to upgrade the gear of my character but it doesnt strike that much so there must be something else that i must do