but here other p2p client will be made...using different p2p protocol ..bitcoin system will only be used for payment..purpose only....More over decentralizing betting will make it impartial and  honest system

Betting has to be concise on a specific event, not abstract. Therefore it makes no much sense, looks like some odd sort of "ad Populum".
Eg. "What will be the outcome of game A", "Who will be the next president of B".
You can't run betting on polls when those polls are generated by the betting system itself, 'cause that would result on the same always: the best spamer wins and I doubt someone is up to promote spam around.  A «guess the number I'm thinking» game would make more sense than that. 

Well, my friend:

If for entering a bet one has to already bet at least once it means the system will never start. Since noone would be able to start the first poll.

Spammers can't "forge results" but get people to vote for "their bet", also those with botnets would have a huge advantage here.
As for generate BC, sure, perfectly possible, you can have several machines generating BC's and output them all to a single address upon creation. Just the value of BC and the uncertain whether and when you'll create some makes such system not profitable.

In the end; you can't run bets on polls generated by the betting system itself. Bet has to be on something the betting system isn't related or can't predict the outcome. That's the essence... 

Botnets aren't just for DDoS, it can be used for other purpouses - can perform anything its master tells them to - including download BC Client and cast votes.

But I'm not being critic, the issue is that you're using votes on polls generated by the system to a bet system. That's a noway thing to do.

One thing is:

Who will win the next game?
- Team A
- Draw
- Team B

This is what uncertain future event stands for.

Other thing would be:

What's your favorite color?
-Red
-Yellow
-Green
-Blue

This is an opinion cast or survey, and it makes no sense to bet on its outcome. Because you're starting a question yourself for a non-event and use the number of replies as the outcome, which becomes a redudancy and a result "ad populum".
Opinions Ad Populum are natural fallacies, like "Many people believes in God" - such has no influence at all to determine whether God exists or not. People beliefs and likes/dislikes doesn't qualify then to create valid results on itsown about anything. 

People beliefs and likes/dislikes doesn't qualify them to create valid results on its own about anything...

You are very correct...

I'd like to see a sports or predictive trading platform such as betfair come to the cryptospace.