If you are the only guy who knows X business process, congratulations! You've got yourself a comfortable trap and not much leverage for a higher pay raise or transfer because you're needed at X forever.

Not all of us are that lucky to have incompetent managers that allow that situation to play out.

But this still ignores the larger problem. Highly skilled workers as a class are still not receiving their fair market rate compensation because we cannot negotiate as a whole.

Your base pay should be much higher than it is and should allow you better opportunities for higher pay in negotiations.