Silicon Valley might be competitive, but it's also a breeding ground for friendships among its famous execs.
The Twitter CEO's fintech company, which owns Cash App, is squaring up to the no-fee online trading platform.
Some of their more extreme habits — like Twitter CEO Jack Dorsey's proclivity for fasting — have provoked criticism.
For tech founders like Elon Musk and Jack Dorsey, it took a couple tries before they launched their massively successful companies.