There is a reason why they provide "garbage" services compared to other places and that is completely down to their company policies, not because they want to scam you. If you live in a remote region where you can only sign a contract with one ISP, that also influences their price to quality efficiency. After all, it's an internal market where they have absolutely no competition, so why should they give you more for your money?
Either way, the quality of your connection shouldn't really matter in this discussion, as we're talking about the morality of selling your info without your permission.
When it comes down to that, I do think that we shouldn't go and blow this out of proportion, like I said earlier. They won't put your info online for everyone to see. They won't look at your old photos or dickpics that you might've sent to that one girl 6 years ago and share them for the world to see. The line has already been drawn in that regard. They're COLLECTING your info, not SHARING it - and no, selling it to various marketing companies does not count as public sharing.
The point I'm trying to reach here is that we COULD be arguing about them selling our info without our permission, but you CAN'T say that you're going to be damaged in any way. It's just a discussion about the moral implications of taking something that may or may not be categorised as theft. The theft part is the part we're supposed to argue about here.