Yes, they can. The idea that they will do nothing because they have to have a job is a myth. Yes you generally need a job in the world to survive, but at some point people will decide that the costs of "just surviving" in society are too high. They can and will quit, and when they do, it will be en-masse, and the whole system will fall to pieces.
The idea that they "can't quit" is what companies who abuse the little guy count on, the mentality that they just have to suck eggs because they need that job so badly. It's happened elsewhere and it can and will happen here if the few continue to abuse the many.