One of the best decks in Hearthstone for a while that plenty of people used involved nothing rarer than a common card you could forge easily (The priest draw deck). Good cards make it easier but it's all about the player. Basically it's only pay 2 win amongst baddies.

Also Arena involves no pay 2 win whatsoever. Also if someone is going to mention the Arena is "luck of the draw" (ie getting good cards), then don't bother, because there are people who can win enough Arena to be self-sustaining.