Ironically, PayPal's core business _is_ security. The founder's interview [1] describe the beginning as a constant race against fraud, which no other bank was

Ironically, PayPal's core business _is_ security. The founder's interview [1] describe the beginning as a constant race against fraud, which no other bank was willing to compete in: "You're going to go bankrupt when the chargebacks start". The was a locked room with a screen-and-keyboard-only computer where you could research about transactions and find suspicious and fraudulent ones. According to the founder, it became PayPal's core asset. [1] in the book Founders At Work, which I recommend.