The most valuable part of Paypal is the systems and strategies they've invented for risk mitigation and fraud prevention. Before they developed those systems,

The most valuable part of Paypal is the systems and strategies they've invented for risk mitigation and fraud prevention. Before they developed those systems, online payment aggregators were a nonviable business. Many people in the late 90's and early 00's felt that it was a failed experiment and that the risks were just too high. This after a long list of failed startups and failed infinitives at existing banks. Yes, it can seem very obtuse. But they are in a risky business. Without their anti-abuse measures (which every other merchant aggregator has cloned to some extent), this niche would not exist. You would have to get your own merchant account if you wanted to sell online.