No, I would not kill anyone even if you change that to "worst enemy" and add a few zeros to the 200 million.
Reason? Because the guilt would not be worth it.
LoL. These threads are always funny to watch atheists freak out and say it's not worth it - and others to be like 'hell yeah I would.' I like the differences and calling people out on things.
For 200 million - I would kill a human that I get to choose - But an ex best friend? It would seriously depend on what they did to me or to others - And if they have children - Or what their life plans would be.
Probably not my ex best friend.
I suppose this hypothetical involves the premise that you are for sure not going to get caught?
Its one thing to 'say' you would kill someone and quite another when it comes to actually doing the deed. I do not speak from experience here...but from others experiences who have related it to me.
Killing a thinking, breathing human being who has family and friends that love them, depend on them, etc....would be a very difficult thing to do... The more you think about it the harder it would be to do. Even if it was a stranger it would be very hard... killing an ex-best friend would be harder for you know more about them and their family and friends etc.. I wouldn't do it for any amount of money.
If someone offered me 200 million to kill hitler or Osama bin laden... no problem... Give me a gun, a time machine, etc.. and I'd try to do it.....just to try to avoid all the horrible death, agony and shit they brought upon so many. Hell I might even do those guys for free.
I think it is sad that people will go to great length to kill their spouse for the 150k insurance policy.
Allow me to first ask a different question: would you have yourself killed for 200 million to be given to your (ex) (best) friend?
And before old or sick people respond, let's assume you have ±60 years remaining of a relatively good and healthy life.
back to the OP question: No, I would not kill anyone for money. I'm not sure if I could kill anyone for lives, I can probably risk or destroy another's life in order to rescue others, but I doubt I could do an actual trade (for instance in a bizarre hostage situation).
The thought of the guilt I would have makes me say that I would not. Although the what I could do with the money (save lives, etc) might outweigh the murder (if it ever could). If it was for personal gain, I would not want to be that person.