Also, you need to be lucky enough to somehow move into a team that uses kdb heavily (this usually happens via an internal move within an investment bank). Learning it using the tutorials is not the same as implementing it in a live environment, and the tutorials probably won't be enough to get you a job/contract. If you could say something like "I've worked on the FX desk at JP Morgan, where we used kdb daily", you'll be hired everywhere. Basically, you need a bit of luck in the first instance to get into a kdb focused team that can train you - after that, you're sorted!
Historically, an APL background was a good indication that you grok the apl/k/j/q mindset, which is very different from the Algol (c/c#/Java/pascal) world and also from the Lisp world.
