Why do candidates stay in the race when they have no chance to win?

[hotpprs]

I started replying about this on another topic, but I think it deserves a full topic.
Why do candidates stay in the race when they have no chance to win?
I replied something to this effect about Newt, that he has no chance to win and should drop out. But thinking more about this later on, that's not necessarily true.
If Santorum and Romney have no major health issues, don't drop dead, have no unknown scandals crop up, then I think Newt has no chance. He is too far behind and would be the odd man out even in a brokered convention because he will not come in even second with Santorum winning Ohio, Tennessee and PA.
But if Romney or Santorum have to drop out for some unexpected reason, maybe he does have a chance?
Also, candidates may just stay in to make their policies relevant during the convention.
Or just to position themselves as VP.
Or maybe they just have delusions of grandeur?
To play spoiler?
This post is directed more about Newt then Ron Paul. But can easily be applied to Ralph Nader, Ross Perot or George Wallace.

[ajb]

I think once someone's in the race the question isn't: why do they continue.? It's: why would they drop out? Your chances of becoming president are higher if you stay in the race (even if only because you're now a thousand-to-one against, rather than zero). You get lots of attention and people give you lots of money. You have the chance, perhaps, to talk about things you care about. And you've worked your whole life for this moment; why would you give up before the very end?

I think when candidates step out, it's more because they think they have something more to gain by leaving, like a better chance four years later, or some other deal.

[Fmr President & Senator Polnut]

Numerous reasons
* Ego
* Point to make
* attempting to gain influence over party platform
* they can afford to
* they hate the front-runner

[Tidewater_Wave]

If you have any chance whatsoever to be in the race then you do it because the possibility is still there. It means alot to the candidates running. Also, money is just as big of a factor. As long as they can afford it, nothing is really stopping them. Support leads to money which is why it is often the front runners and winners who only stay in.

[© tweed]

you're operating under the assumption that the only legitimate reason for running is to win.