Buying players of the auction house

You know what? I don't understand why the hell  EA makes a card you bought off the auction house, and now I can't sell that player. I finished the game-changers challenges, and I pulled 96 over Khalil Mack, now I want to sell 95 over Micah Parsons that I BOUGHT off the auction house, and now he is BND. Now he gets to sit on my bench when I could've just sold him. Now I could understand if I pulled him in a game changers BND pack or any of the BND packs but now I just lost all the mfckn coins. I'm beyond pissed don't understand this game