Warren Buffet, man, is smart.

He wrote:

Charlie and I believe Berkshire should be a fortress of financial strength — for the sake of our owners, creditors, policyholders and employees. We try to be alert to any sort of megacatastrophe risk, and that posture may make us unduly apprehensive about the burgeoning quantities of long-term derivatives contracts and the massive amount of uncollateralized receivables that are growing alongside. In our view, however, derivatives are financial weapons of mass destruction, carrying dangers that, while now latent, are potentially lethal.

When did he write that? 2002.

His stock has gone through the roof since then.