Just to throw in my 2 cents (sorry couldn't resist. :-)
As long as a post or comment makes a total of $0.02, then it gets paid out, whether it was one 2 cent upvote, or 200 $0.001 upvotes. In other words, I don't know why your followers are cutting back their upvotes, but you still are receiving benefit from them, though a smaller benefit of course. For example your current post has $1.28 in upvotes from 14 votes, if someone upvoted you with $0.001 it would still benefit you, because your post made over 2 cents.

I can see the usefulness of dustsweeper, because I have a 2 cent upvote value, and my account is worth around $450. This is a massive sum of money to many people in the world, and it must be frustrating to upvote a friend's comment with $0.01, and the friend never gets any benefit from it (this is assuming that your 1 cent vote was the only vote). All the money you put into dustsweeper comes back to you, as it doesn't make you any money, but it does capture votes that would be "rounded down" and simply disappear.
As for your point about them going bankrupt, I don't think that will happen because they probably have a large amount of "float". Just like a store that sells gift cards that take an average of 6 months to redeem, there is a lot of money in it that is just waiting to be paid out. During that time the account can grow etc. to catch up. In your example of the exploitation, buying lots of small votes for a single post would not trigger dustsweeper if the total upvote was over 2 cents. If it added up to $0.015 cents, then dustsweeper would kick in a small amount once to bring it over 2 cents. To try to exploit it, you would have to buy 1 tiny upvote for each post/comment, which would be time consuming, and you would have to have massive numbers of active posts/comments to do this. Hope this helps.