It's called a tip jar effect. Someone posted about that. I'd link if I can find the post or if it isnt considered spam. In any case, I initially felt it unfair, too. But really, the people who get "tricked" into opening a boosted post wouldn't come back if the content wasn't to their liking. And with payouts degrading (I forgot the exact term used), the boost value is actually decreased over time. Ultimately, a lot use said bots as a marketing strategy. If they offer good content, then whether they boost the next post or not, the genuine followers he gained previously would click on his post. Of course continuing the marketing campaign doesn't hurt either. This, of course, is just my opinion.