A filthy rich ad man bets a corporate rival that he can live on the streets of N.Y. without the comforts of home or money for a month, which proves to be tougher than he thought.

basically what everyone else has said, what u got is a concept. an interesting concept. but my biggest problem is i dont get the genre of the film with this. This could describe a comedy, a dramatic piece, a crime piece, etc. I just think u need to dig deeper and get to what your story is really about.

>>>For this to work, there must be a Sin? we have to want the ad man to get his comeuppance
>>>In the end he will have to do a Completely unselfish act? to get his old life back.

Yep. That's the standard formula for %1 stories.

For this to work, there must be a "Sin" we have to want the ad man to get his comeuppance. Plus I am not convince about the "Bet" angle.
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"After ignoring a homeless man's a plea for money, an arrogant ad man wakes up to find himself homeless, penniless and unknown to everyone including his friends and family."
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First he would be lost and confused, Just when all seem darkest a homeless 'mentor' would take him under his wing. (Would be his guide)

However, even though he would be confuse at first, because those ad guys in New York work 80 hour weeks, I can't see this guy simply sitting around with a sign saying feed me. That kind of work ethic doesn't just go away.

Since ad sales are about how you connect with the consumer, I picture this guy figuring out which signs work. "Hungry need food" "Help a Vet," or whatever.

Then he would create the perfect "Ad Campaign" (As he would look at it) and organize the homeless to get the best bang for their buck when pan handling.
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In the end he will have to do a "Completely unselfish act" to get his old life back.

Hope that helped, good luck with this!