As somebody who's spent decades supporting the Long Now, I believe that a lot of what's wrong in our society is people incorrectly understanding their long-term incentives and focusing on the short term. And I'm happy to believe here that Beeminder's long-term incentives really do work out to be mutually beneficial when handled by you.
But there's just no way I need the mental overhead of wondering all the time whether me paying you when I fail in a given instance really conforms to the ultra-long-term, 12-dimensional-chess understanding of conflict of interest. And then if/when it does, whether I'm failing enough to give you sufficient money so that there's a balanced exchange of value. That is way too much overhead, especially for a tool I'll be using in areas where I'll be hitting my cognitive limits on the regular.
I totally believe this works for some people, maybe most of them, but for me it's a non-starter.