The former, due to both the communication effort required for the 6 billion people to organise themselves and to information asymmetry. If there's some critical information required to make a decision, each of the 6 billion people either has to discover it themselves or trust someone else, and the latter hands power over to those they trust. The man with 5 billion dollars only has to discover it once, and can pay people to assist him which incentivises them to behave in a trustworthy fashion. It's the same reason that the SEC restricts some forms of investments to "accredited investors".


That's quite simple really. The market would ensure that those unable to support themselves financially would be unable to obtain food and would starve to death. (Of course, in practice this wouldn't work and state intervention would be required, but that's true of the market in general anyway.)