I'm amazed that people are still giving money to Howard Dean. He's burnt through so much of it already without winning a single state -- or even ranking 2nd place more than once -- and yet the moolah keeps pouring in.
I think the biggest factor is psychological. Many of Dean's volunteers have so much time and money already invested in his campaign that they can't admit defeat. They feel like their earlier donations aren't really "wasted" until they give up, and they're trying to put it off as long as possible because the thought of throwing so much effort down the drain is agonizing. (Much like money spent on declining stock isn't "lost" until you sell the depreciated shares.)
In economic terms, the time and money already invested are sunk costs: they can't be recovered to any significant degree, no matter how much more resources you throw after them. Although it may seem counterintuitive, it's foolish to allow sunk costs to influence decision-making; what's been spent is already gone, and the decision to spend more must be based only on the current situation and expectations for the future.
Dean supporters should ask themselves whether or not they'd make a first donation to a candidate who is lagging so far behind the leader. It may feel emotionally satisfying to "never give up", but having given money in the past is no reason to continue doing so once the cause has been lost.
Sunk costs have a way of warping our sense of reality and perspective. Just as a woman might be reluctant to break up with an abusive boyfriend because of all the time and energy she's already invested in the relationship, Dean supporters would rather ignore the numerical facts than admit their past contributions have come to naught. Meanwhile, to prove to themselves that there's still hope, they keep forking over the cash.
Unless Howard Dean is planning to run as an independent once he loses the Democrat nomination (*crosses fingers*), he's leading a pack of lemmings over a cliff by using his influence to con his followers out of their money. At least he had the decency to draw a line at Wisconsin.