You appear to have skipped the part where it is clearly explained that introverts are not necessarily shy. Admittedly, it's a common confusion.
Most of the people I know who have 'made it' are the CTOs not the CEOs, but that's started to change since getting into e.f. and running CertSimple.
I met someone who runs one of the top 1000 websites a few weeks ago. Their company is beyond startup size but they still run it. They're the CEO not the CTO, and they're naturally very shy: but they also force themself to ask awkward questions and challenge people directly about non-technical things.