They probably see something else that we don't. I think that as long as people are willing to buy and sell BTCD even though they are no longer able to withdraw or deposit it, there is money to be made out of fees and speculation. Also, in one of my previous posts, I said that once almost all the supply is swapped (which is the case now), it will makes BTCD very scarce and this could trigger very high prices. We've already witnessed a (small) spike (BTC-wise) after the swap deadline was reached and this could happen again (or not).