I have five years more "professional" experience, seems to be the difference - I had verifiable coding experience on open-source projects before that that would have demonstrated those skills. I've got more confident in my judgement but I'm not at all convinced that judgement has actually improved.

Did your core languages change during each switch? What is your current stack/expertise?

I stuck to the JVM (since people seem willing to pay more if you have experience on the specific stack, and my first job happened to be Java); for the last 3-4 years I've been doing almost exclusively Scala.