I'm not planning to sell my cards anytime soon as I do believe the game will do pretty well. It's just that after over a year of playing daily with the initial challenge of getting to know all the cards while collecting more, it feels like there is little to no challenge to the game itself anymore mostly because of the matchup system which makes it feel like skill is totally neglectable. I want to outplay opponents or get outplayed learning something in the process instead of playing matches where the winner is known before the match even started. That is really my only frustration with the game at the moment.
I'll check out DYGYCON