It also backfired on him at the height of the credit crunch. While he was smart enough to write the contracts in such a way that he didn't need to post collateral, he didn't account for the way that someone looking to hedge their counterparty risk with him would behave. When the market collapsed, the buyers of the puts proceeded to short both the equity and debt of Berkshire to protect their investment. http://crookery.blogspot.com/2008/11/valuing-large-options-i... and http://crookery.blogspot.com/2008/05/warren-buffetts-vega-ga... have some of the technical details, and http://www.portfolio.com/views/blogs/market-movers/2008/11/2... has a good general explanation of what went wrong.
Buffett may not have been in the casino all the time, but he had plenty of side bets that could have wiped him out.
PS: Leverage means making money from money you don't have ex: loan on rental property. But to classify as highly leveraged you need to risk 10x or more money than you actually have.
The "money you don't have" part of the definition of leverage isn't necessarily money that you must pay back like a loan or bonds; it can also be money that you may have to pay under certain conditions. Writing naked puts and selling reinsurance is the latter.
From http://community.reinsurance.org/Data/Leverage/Und%20Lvg%202... , we can see that Berkshire's 2005 leverage ratio was 143%. That's fairly low for a reinsurance company, and Berkshire is not highly leveraged.
However, I'm still going to maintain that the marginal increase in leverage from the specific derivatives deal I mentioned was rather high. Most insurance companies have noncyclical liabilities (e.g. the mortality rate doesn't increase in recessions) and procyclical assets(e.g. stocks and bonds that fall in recessions). The sale of puts added a procyclical liability, increasing Berkshire's leverage at the margin.
Thanks for the catch. See my edit above for more.
Berkshire did not loan the $5 billion and receive the options until well after the financial mess...
This is effectively wrong, since the TARP funds were issued after the investment. See the link at the edit above.
In any case, I think that if there anyone who has demonstrated an immense understanding of the American economy for the last 50 years, it's Warren Buffet and his partner Charlie Munger. There is no one/duo that has been more successful at investing and predicting long term economic scenarios over this time period.