A contactless card broadcasts its number the moment a reader gets close enough — through a pocket, a bag, a wallet you never opened. You don't tap it; someone else's reader does, and you'd have no way of knowing until a charge shows up you don't recognize. "It hasn't happened to me" isn't protection. It's luck that hasn't run out yet.
The wear happens quietly too. Loose in a pocket next to keys and coins, the stripe and the chip's edge take a beating every time you sit down or reach for your phone. The scratches build up until the day a terminal just won't read the card, and you're signing a slip or waiting on a replacement.
And even when nothing's wrong with the card itself, finding it is its own problem. Debit, credit, work badge, gift card — they're all the same size and shape, so you end up thumbing through half of them at the register while the line behind you waits. It doesn't have to be a guess every time you open your wallet.