Lol, Musk lost a power struggle, yes. But why does Musk have to personally build something in order to count as a successful CEO? That is a standard applied to no one else. Yes, the earliest form of Paypal was developed by Confinity, but it looked very little like the Paypal after the acquisition. It was initially only for Palm Pilots! X.com had the ability to send payments using email addresses first.

And the decision to buy them (which X.com did) was made because Musk and others (not others in opposition to Musk) recognized the potential in the early Paypal product. Acquiring a promising product that goes on to be huge is the kind of thing a successful CEO does much more often actually coding a new product him/herself.