Yes, lower the points that everyone starts with. Why not just 1,000 and not even have a bonus for the person that picks the highest? Or 20,000 : 500 as 1,000 : 40. Make the bonus for high pick 47!
That should speed the game up without changing the play too much. Right now I'm trying to imagine different scenarios towards the end of the game. Especially as people start getting getting under 500 points. If it's 700 to 330 to 141 to 50 to 33 to 10, how do you think the game will go? The person with 700 can just bet 331 on the next round guaranteeing 500 points for a net gain of 169. Everyone else will have less points, plus one of them will be in the pond. The person that had 700, now has 869 and can follow the same strategy as picking one point more than the second place player and the game will end eventually with him being the winner. Everyone playing will know this is going to happen and won't feel like going through the motions. Big flaw if it goes down like that.
I hope at the end of the game the players with the lead are close to each other. The problem with the bonus points won't really be apparent until everyone but one player is under the bonus amount. So, perhaps in a later version of the game, the bonus amount could be varied during the game to reflect the mathematics of the game itself or just eliminated.
What will make it interesting is if three or more people are just over the bonus amount and try to psyche out what the other close players might be planning on betting. They could all bet a small amount, in which case some other player might get the bonus and join them among the leaders, or one or more of them might bet lots while one bets small to save his points.

Yes, this game is tougher than it looks and the rules have a lot to do with which strategy to try depending on the score and who're your opponents.

If this game becomes one that us members (Paying or not) can create, I propose making it possible for the game creator to be able to set the parameters for starting points and bonuses(if any), along with the usual things like days per move and minimum and maximum players.