What do "sure-to-lose" candidates stand to gain by running for President?

[Bicoastal]

This question has haunted me lately...people like Chris Dodd and Mike Gravel are spending untold amounts of their money and time, and for what?

Both of these guys must have known they didn't stand a snowball's chance--even if a household name like Clinton or a rock star like Obama wasn't in the running, both men must have known that they'd never catch up to Edwards, or Biden, or Richardson, or even Kucinich. No matter how much they tried, they were virtually assured a place in the rear. So why do it?

To possibly garner the nod for Veep?--I can think of plenty less expensive ways of doing this...

To gain national exposure?--Doubtless useful for a political animal, but again, at what cost?

To provide "a different perspective" at debates?--Well, what's the point if you end up looking like an unpopular loser?

To honestly make a difference?--I'd like to believe this, but honestly, the cynic in me says no sane man or woman would embark upon a harrowing journey such as the electoral process without first calculating the cost of losing.

Or are some people (like 2004's Joe Lieberman) so deluded that they honestly think that the other +95% of the elctorate WILL warm up to them if they make enough speeches and attend enough BBQs in Iowa?

The same goes for the long-long-longshots on the other side, such as Tancredo and Hunter--Why do it?