No leader should expect anything different from their people. It is your job to align the incentives so that what is best for the employee is to do those things that are best for the company. If you are relying on people to do what is not best for them out of loyalty to a corporation/startup/vision, you do not have an accurate pulse of the modern work force.
And yes, when a leader or company looks like it is going sour, sometimes employees act in bad faith for their own self-interests. When that happens, question why -- what is it that makes them think bad faith actions are more beneficial than helping the company. Don't just fire and forget... do some self-critique to find out why someone who was smart enough to be hired in the first place lost faith in your leadership. There are likely important lessons there.