They were also almost all men. The fact that they had testicles didn't cause it anymore than the fact that they went to University. It's odd that the people will try and find causes that have at best an indirect effect on the collapse, but still try and denounce things like deregulation or lack of more regulation that had a direct effect on the collapse.
The Ivy League, and particularly their business schools. http://www.projo.com/opinion/contributors/content/CT_hassett22_02-22-09_0NDBQJT_v16.4003053.html
this discussion deserves its own thread. i don't think there is any doubt that the buddy buddy nature, and lack of oversight inside the banks, was contributed to by the fact these guys all come from and exclusive club. its not just wall street, its growing up with privaledge. you have a bunch of robot yes men walking around these banks telling each other how great and maganificent each of them are, no that product isn't going to collaspe, you're wonderful, you went to the same school as i did.