It seems pretty clear that they stayed after any illusion of that fell away.
See abusive relationships or this handy article http://www.issendai.com/psychology/sick-systems.html
Due to the low physicality of the work, there are likely people who consider it easy work, despite the psychological impact that seems obvious to you or me.
I don't expect these contractors to get much long term benefit from the position. And it sounds like most quit or get fired.