44. Garrett Camp

Cofounder, Uber; cofounder, StumbleUpon; founder, Expa

Though he has shifted his focus to other projects, Camp is a multibillionaire thanks to his stake in the ubiquitous ride-hailing service Uber; his net worth is now at $6.2 billion.

This year, Camp launched the startup incubator Expa Labs, which has raised $100 million and will focus on providing a more hands-on experience to smaller cohorts of budding tech companies. Last August, he also bought back a controlling stake in StumbleUpon, the content-discovery website he cofounded as a graduate student in 2001 that learns what users like and recommends related sites to them.