I want to pick up on Matthew's earlier comment about how you've got to go slow and then go fast when you can.
When you compare the Internet and the payment card system, what's interesting is that the way we pay for stuff has barely changed at all in 70 years. It started with a paper card and then we went to a plastic card. Then we had two problems, transaction speed and fraud, so we moved to a mag stripe. Then the crooks figured out how to do the mag stripe, and so we moved to a chip card. Since we've gone to chip card, in-person fraud has gone to zero, but we have this online problem, so now we're putting it in the phone.
What's important is that the way users pay for stuff across the globe has barely changed at all in 70 years. On the Internet, it's changing every single week. Users can't keep up.