upgrade card is genuinely the worst card in the game it feels like, needs a buff - either exhaust or retain or something.
Try upgrading the same card in while and thin your deck, upgrade is actually kind of good
It tends to fall off though by the time you get to mid-game if not earlier. The only time I see to want to use it is when I don't have any coin cards in my hand and I have an overkill situation.
