You're right, of course. Nobody's forcing people to borrow money from banks. In theory. But there is still something that needs correcting. Those people are consumers. They've been born by consumers, they were brought up to consume, every TV-ad, every billboard has been telling them to consume since the day they were born. They borrow money to consume and then work to pay off their debts. Well, everything IS fair and right... technically.
They're wrong to protest, of course, but the system that creates brainless consumers should also be corrected somehow.
These people can't express their thoughts, but they do feel deceived. They've been told to consume and so they did. Now they cannot and therefore - protest.