And Stripe, there was huge pent-up demand for a PayPal alternative before they came on the scene. How could anyone say that was a "black swan" bet? It doesn't make sense.
Pent-up demand for a PayPal alternative are from sellers who have a customer facing PayPal payment mechanism. Customers know they're paying with Paypal and customers usually have a PayPal account they use to pay you with. PayPal can hold on to customer funds like a bank.
With Stripe, a customer doesn't know you're using Stripe and if they had a Stripe account they wouldn't be able to see all the purchases they made at various sites that used Stripe, they're just not the same thing.
PayPal now owns Braintree, so they now do compete with Stripe.
My point is there is no black swan here. Far from it. It makes no sense in this context.
I think most investors would have claimed that Stripe would probably make money but would never get huge. Now they're pushing $2B - that is an extremely unlikely outcome and so fits sama's definition of black swan.
I do not recall Stripe being positioned as a PayPal alternative really ever, but certainly not when it launched.
I also believe that Sam was first made aware of Stripe much earlier than most people and it probably did seem like quite a black swan at the time.
I know the very first time that I heard the idea for Stripe it was definitely considered a "crazy" idea. I would easily categorize it as a black swan investment.
It obviously was a difficult bet - young founders, powerful incumbents - plenty of risk and unknowns.
That said, I believe a good seed investor will spend a lot of time with the founders and the team before pulling the trigger. You'd be surprised at how few investors actually do that.