A Curator is a failsafe mechanism that indirectly prevents malicous actors from executing 51% attack. Curators do not add centralization to the DAO: they are nominated by the DAO Token Holders themselves, and can be fired at any time, for any reason. Curators curate the whitelist, the list of Contractors authorized to receive ether from the DAO. A Curator therefore holds two primary functions:
First, when a DAO Token Holder submits a Proposal in the form of a smart contract, the Curator checks that the published Contract on the Ethereum blockchain matches the source code the Contractor claims to have deployed (this is done by comparing bytecode).
Second, a Curator confirms that a Proposal comes from an identified person or organization. This is done by asking the entity submitting the Proposal to send a signed transaction with a certain set of data only known to the Curator and the author of the Proposal, thereby confirming the author of the Proposal.
The above are the only two functions of a Curator. For clarity, the following tasks are therefore not the role of a Curator, but instead the role of the DAO as a whole:
Evaluate whether a Proposal is ‘good’ or not. Audit the Proposal’s smart contract code. Provide legal advice regarding the Proposal (if any). Take responsibility for the Proposal.
Edit: For the interested, the distinction between a pyramid scheme and a Ponzi scheme is that a pyramid scheme is relatively more upfront about how it generates returns, and relies on the investors themselves to recruit new investors, not the fund manager.
..and to convert that to USD or whatever you can even use https://duckduckgo.com/?q=1+ETH+in+USD&ia=cryptocurrency or check the price directly at one of the exchanges that trades ETH/USD, like https://www.kraken.com/charts.