They did not really earn those $100 yet, not until the payout.
Don't get me wrong here. I think automatic votes do have their place as they work basically like subscription fees.
It's only a bit harder to adjust an autovoter for the fluctuations of the price, and that is mostly what can lead to surprisingly high rewards. Which is exactly why downvotes have their place too.
It might actually be helpful, if there was a tool to automatically lower or raise the vote of an autovoter in the event of price fluctuations. I wonder if anyone has made one. Last time I checked, hive.vote didn't have any.
Other than that, the one using an autovoter should set the vote percentage considerably less than what they would organically vote. They can always correct the vote upwards later if they so wish.