I said this in another comment below:

> If you sell the Ether, you no longer have the Ether. If while you're holding the loan the price of Ether goes up, you benefit from that. Of course, if the price of Ether goes down, you're at risk of having your loan liquidated, but that's a requirement imposed by the system to maintain the Dai peg.

maybe they want to leverage? take out a loan secured in eth, and use that loan to buy more eth