The chip is a copy-protection mechanism. This means you can't do a man in the middle attack (in your words 'steal he swipe') because the chip on the card has challenge-response protocol to authenticate. Even if you somehow steal a single response, next time the challenge will be different.

That is not to say it is impossible to get the secret inside of the chip, but it is hard, often requiring partial disassembly, some sort of side-channel and you will often destroy the card in the process.