1) Too much leverage, without understanding the risks.
2) Trade imbalances causing capital flow imbalances.
3) Complete lack of regulation and lack of enforcement of existing regulation.
4) A culture of "gotta have it now."
5) Productivity surge that couldn't last.
As for greedy CEOs, many of them were non-productive parasites on the system (John Thain, etc.), but it wasn't their fault.
And as for capitalism, my observation was that it's going to change drastically, not that it was at fault.