Its an interesting idea, but actually not too dissimilar from concepts that already exist in the marketplace. My medical aid scheme, for example, has a loyalty program that rewards you in this manner for making healthy lifestyle choices. Eat healthily and get points, go to gym and get points, stop smoking etc. Points can be redeemed for rewards like discounts, holidays, etc.
From a commercial point of view its in the interests of the medical aid company to sponsor these prizes because its clever actuaries have worked out that if their clients are motivated to become healthier, they will actually generate a positive return on investment from the loyalty program due to decreased medical claims over the long term.
But an interesting additional element your game alludes to is competition. People will strive to do all sorts of things in the interests of winning, that they wouldn't necessarily otherwise consider, or do with as much zest, at least. Leader-board's are now commonly used in marketing to build communities and fuel participation.
Its a good idea and I think it would work. Coding the game would be relatively straightforward. Tough part would be finding sponsors. Who's going to reward me when I earn 30 million points for finally taking a "How to be nice to people" workshop?