One possible reason why BFV sales are down

No one is grabbing you by the ear and forcing you to buy the game if you do not like it, it is totally YOUR choice whether to buy the game or not. You also have a good timeframe to request a refund if you do not like a game you bought on origin, so if you buy a game and you didnt like it and you KEPT IT WITHOUT REQUESTING A REFUND, it was YOUR choice, you cant blame the devs.