Back then, voting bots were mainly used to people to increase there own rewards but projects used them as well to get many eyes on things. I used to be a member of the silvergoldstacking community and we used to use voting bots to promote raffles and contests we were hosting for STEEM. Mostly they were used for self voting but they were used to promote as well.
There were times when people were paying for then they were getting back. For instant votes services, like send 1 STEEM and get a 10% upvote we could see what a 10% upvote was worth before paying. With bid style platforms, it was a gamble, the more people online the less the return and many times negative. I do remember when post rewards switched from 70/30 to 50/50, alot of voting services want into the red regarding ROI.
My point with the price of HIVE is, that HP would have so many more use cases if it could be monetized. Few people buy HIVE today, all hoping the price will go up, back then, lots of people bought STEEM to use it. Today we can either use our HP to curation to delegate it to some project that uses it for curation and gives you a HE in return.