Ask HN: What Laws Limit EULAs?

What laws determine the limits of EULAs attached to products, e.g. websites?

It wouldn't make any sense if I state that all property of my webpage users belongs to me if they dare to use an adblocker - It wouldn't be enforceable even if they accepted the rules on my website, right?

But even if the scope of consequences is limited to whatever happens between the client and the product, these consequences can be severe. Do we have historical examples of services exploiting users legally through EULAs no one reads?