"Let me emphasize again that cost-free float is /not/ an outcome to be expected in the [property-casualty] industry as a whole: In most years, industry premiums

"Let me emphasize again that cost-free float is /not/ an outcome to be expected in the [property-casualty] industry as a whole: In most years, industry premiums have been inadequate to cover claims plus expenses" [buffet]. So another thing to consider is that if the insurance company is a better investor than you are, the proposition might not be a negative expected value bet for you at all. [buffet] http://www.berkshirehathaway.com/letters/2010ltr.pdf http://www.berkshirehathaway.com/letters/2010ltr.pdf