Anyway, we have a whole elaborate essay on why there's very much the opposite of a conflict of interest: https://blog.beeminder.com/defail/ (about how Beeminder revenue is proportional to induced user awesomeness)
There's a key faulty assumption that may make it seem like our incentives are more perverse than they are. Namely, it's not the case that Beeminder goals are binary things that you either succeed or fail at. They're things you make long-term graphs of, like averaging 10k steps per day or working 40 hours per week. You pay Beeminder because your overall progress is much greater with Beeminder than without it, even though the specific moments you pay are kicks in the pants when you've deviated from your commitment.
I'm definitely interested to hear if any of this is persuasive. We hear the perverse incentives thing a lot so we need to figure out how to convey our apologia much more concisely in our intro material! (And thank you for voicing it!)