Having left several jobs I can tell you, they will survive without you, no matter what you think. Unless you are a founder or a shareholder, all you have is the

Having left several jobs I can tell you, they will survive without you, no matter what you think. Unless you are a founder or a shareholder, all you have is the loyalty your employer has carefully cultivated. I don't think you have any moral or ethical obligation. It might not even make them mad when you leave - if they're doing their job properly then they've already prepared for the possibility of losing an 'indispensable' employee.