In 2009, Patrick and John Collison went to Startup School in Berkeley, got sushi in Potrero Hill afterward, and decided on the walk home to start Stripe. The reasoning, as Patrick remembers it, was that “we might as well because it probably won't be that hard.” It took two years to launch. Seventeen years later, at Startup School 2026, he talks with YC's Harj Taggar about dropping out of MIT twice, why founders should ask what happens if they succeed, and what Stripe's own data says about the best time to start a company.