Where is the moral quandary in moving to higher paying jobs? Employment is at will. If your company can't afford to lose you they are welcome to sign you to a long term contract like sports teams do with their players. But they never will because they lose the right to fire you whenever they want. You owe them nothing.
You may never see this, but I want to clarify. I have no qualms about jumping ship; I have and will again. I was referring to the morality of doing bad work and propelling oneself upward on the good work of teammates. Writing code that works but is impossible to maintain and selling oneself as a hero is, in my opinion, a Shitty Thing To Do.