Why not ask that question of 95% of the clubs who go in for competitions? Only a handful ever have a chance of winning.
I agree that if you're in a strong enough position you should try to win, but the idea that only winning matters seems to me to display the arrogance of the fans of top clubs.
Surely football is its own raison d'être? After all, the majority of players worldwide never win much, and the majority of true fans never witness their teams lift a trophy.
I realise that your point is more to do with the idea of throwing a lesser competition deliberately, but I'm questioning the accepted wisdom that the only point in playing or watching football is to win. Only a lucky few are in that position.