I sometimes go to a power lifting gym, it's bad ass, all welded steel and duct tape pads.  The walls are unpainted plywood with banners all over.  It's pretty cool. Anyway, there's guys there that push ungodly amounts of weight, and I've never seen anybody do a squat with more than 3 plates without a spotter.  It's just way too easy to fuck yourself up with that amount of poundage on your back.