I believe this technology is usually implemented smart card style, ie in a tamper resistant package with an integrated cryptographic processor. So while yes, yo

I believe this technology is usually implemented smart card style, ie in a tamper resistant package with an integrated cryptographic processor. So while yes, you could lose it it wouldn't be (reasonably) copyable - and you'd be in a similar situation to if you lost your keys or your credit card. In this case you'd need to revoke the keys, similar to changing your locks or credit card numbers. I also believe the contactless payment functionality should at least have an option (or require) a separate PIN.