Ironically, Lake understands better than most what PayPal is up against. As a sideline to his writing, Lake consults with financial institutions about their communications systems -- for example, the automated calls you receive when your credit card may be compromised. He's familiar with the fraud protection process, and he thinks PayPal's has plenty of room for improvement.

"There's a guilty until proven innocent bias to it, and that needs to change," he said.

PayPal can't afford to be complacent much longer. The field that it once monopolized is now full of competition: WePay, Square, Stripe and smartphone-based systems like Google Wallet are only a few of the up-and-coming rivals.

"We are committed to getting back to being the center of our customers' financial lives," PayPal's Nayar pledged. "Big changes are coming."