If the usage of bots is anything to go by, it just shows how widely popular bots are. However, bots are just that - automated software to upvote on posts based on the inputs. For most users it returns a loss on their spending.
The very few who do profit are the ones who bid big amounts. For example, if a bot has a maximum vote value of $10 and most people are bidding 50 cents to $1 if someone comes and bids $5 he is going to pull most of the bot's voting power. That is how bots work, skewing profit towards heavy bidders.
If you want your post to be "seen", then you have to spend a large amount of money on various bots. Bidding 50 cents on a single low powered bot for an upvote will not do much for a post, something that can be figured out by looking at the upvote values of the hot and trending pages.