They would sell Auctomatic for $5 million and move on to their next idea, developing an easy way to accept mobile payments online.

In 2009, the brothers started writing code for what would become Stripe. Soon after, they secured funding from start-up incubator Y Combinator, where they caught the attention of investors Thiel and Musk.

In 2016, John became the world’s youngest self-made billionaire, taking the title from Snapchat co-founder and CEO Evan Spiegel. Today, Patrick is Stripe’s CEO and John is its president.

When they’re not running the company they co-founded, both are avid readers (the two are said to own more than 600 books) who like to run and travel.

Along with their talents, the brothers’ trademark humility — despite their billionaire status — has earned them the confidence and enthusiasm of investors and clients.

“Heartening as the success to date has been, we are so early in accomplishing the goals that we set out for ourselves,” Patrick told Forbes in 2016. “If anyone here believes that Stripe has already made it, that would be hugely problematic for us.”

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