Once during college a number of students began protesting (insert random cause here), which entailed them taking their round the clock stand by camping out in front of the student union. It wasn't long before the protesters started looking more like the homeless than students. Not because the students went unbathed for their cause but because the homeless recognized an opportunity and capitalized on it. Twas brilliant. Turns out, it is not cool to sleep outdoors say on a sidewalk or bench if you're simply homeless. You may catch a couple hours of shut-eye but it won't be long before you're nudged by one of the boys in blue and told to keep moving, but if you're protesting something, you can set up tents and bbq grills, and stay for months.
Pretty sure that's what's going on with Occupy Wall Street.