[IronUnkind]

You should nitpick more carefully. The areas in my reply which you highlight were both sarcastic.

Let me be clear. Button three is the most obviously moral choice. Non-participation is significantly less moral. And it is decidedly immoral if we assume that refusal to participate will not influence the government policy. For the sake of the question, I make that assumption.

The main reason that it's easy to become a "desk murderer" is disassociation of one's actions and their consequences. David's scenario does a nice job of removing the desk, and because of this, I doubt that even very greedy people would fail to choose button three (at least not on day one). Some might pass the buck, but only a very few would take the cash.