The 20 - 30 cents in the above scenario sounds about right. That's a 20% to 30% ROI, I can see why so many people do it.
The trick is to find undersold bots if you're going to buy upvotes. Also, to avoid buying upvotes on platforms that take benefactor rewards is probably wise.
It appears to me that this is happening as much as it is because it is profitable, but I'll check the links above, thank you. :)