Buying insurance against an event with fixed probability, what should the insurance company's profit margin be

I'm trying to buy $250K of coverage against an event that is known to occur with 10% probability. Thus, the expected value of this insurance is $25K. I'm getting a quoted insurance premium of $57K, although I am told that this is negotiable, but I should provide an offer. What's a reasonable risk premium for an insurance company to charge?