... and no Warrants shall issue, but upon probable cause, supported by Oath...
I am raising the amount of cards because seeing them all would, in my opinion, immediately reach the bar for probable cause.
Cop with a card reader sees a gift card
Cop does _not_ have probable cause and cannot use the presence of a gift card to get a warrant.
Cop with a card reader sees 143 gift cards
Cop now has probable cause and I would expect to have no difficulty obtaining a warrant.
If there were a bunch of legitimate reasons for having 143 gift cards lying around then their existence would not automatically create probable cause. That's why the number is important.