I have a pretty similar story. I spent 7 years working as a subcontractor for a big telco with CORBA, pthreads and the ACE reactor library. First week, I halted a whole contact center service by adding a sleep call to the codebase (it was on UAT environment). Fast forward several years and I could effortlessly debug cores with thousands of threads, reason about semaphores, reentrancy and even tell the difference between the POA and the BOA Orbix adaptors. I began to become the mythical guy who knew what everything did not because I was technically good, it was because I understood the business and how it mapped to the different architecture elements.

Then I felt like I could spend my whole career there and decided there was a whole world out there in the web, began to learn PHP in 2004 until the mythical "blog in 5 minutes" Rails demo appeared. I switched jobs in 2007 and I have never looked back.