Just because you've witnessed that doesn't mean you need to adhere to that mentality. There are sick-minded people everyone, it doesn't mean you have to join the party.
Let's up the stakes, you could put a gun to my head and say "Kill that man across the street and I'll give you this case with 100 billion in it, or if you don't, I'm going to shoot you in the head"....frankly, I'd say pull the trigger. As I stated earlier, you can't put a value on a human life.
Eh, that's not really comparable. The original question was whether you would kill for money, you're asking whether you'd shoot for survival. The case with 100 billion is irrelevant when someone has a gun at your head. If someone gave you the choice of either killing someone else or being shot, you'd kill the other person. Humans have a primal instinct to survive that overrides any sense of morality. It's why we'll kill our attackers in self defense if we have to.
Regarding the original question, I'd definitely consider it. But I don't think I would go through with it. At the end of the day, money can only buy you so much. So long as I can afford a comfortable life on my own merits, where I don't have to stress about bills and expenses, I am happy.