My memory is a little fuzzy, but back in 2012 or so, this programming whiz applied for a job at Square on the security team (I think?). He was impressive, and had written an SSL implementation (EDIT: it was actually a certificate authority) entirely in Ruby. Breezed through the coding challenges. Just our luck that one of the interviewers was the actual author of that implementation!
Seriously, it was really just luck. It makes me wonder how many people successfully bluff their way through their careers.