I would do what they said, I have already been stabbed in a similar situation, and I learnt my lesson, your money is not worth it.
Even if you are willing to die to spend his lone bullet (which is impossible to know he has just one anyway, but I will go with it) chances are if you try and stop him the gun will go off accidentally and possibly hit one of the friends you were trying to protect and while not really your fault, you would have to live with that.
Even if you are willing to die to spend his lone bullet (which is impossible to know he has just one anyway, but I will go with it) chances are if you try and stop him the gun will go off accidentally and possibly hit one of the friends you were trying to protect and while not really your fault, you would have to live with that.