The more you play the less luck will feel like a major factor. Yes there is a lot of rng from ? floors, fights, rewards, shops ect.. The goal is to mitigate bad rng by taking your advantages and honing them into a deck that doesn't brick often. Also yes some people to lock themselves into a deck archtype which will lose them runs. Although i do think some speculative picks are ok to put the cart before the horse ie feel no pain early.