Evan Spiegel — Snapchat

Evan Spiegel left Stanford three credits short of graduating to run Snapchat full-time, and by 2017 became the youngest billionaire CEO on a major exchange since Zuckerberg. Snap Inc. went public at a $24 billion valuation, and he famously rejected a $3 billion acquisition offer from Facebook in 2013—a 'no' worth over $30 billion at peak. He now lives in a $120 million Bel Air estate. Spiegel's decision to reject Facebook's offer was 12 times smaller than Uber's peak valuation of $120 billion (#8 Travis Kalanick), but his enduring leadership contrasts with Kalanick's ouster.