If my wallet would be big enough I would take the insurance if it existed and only costed a small percentages of what I have.
The only problem is, how would the insurance company verify if you indeed lose your wallet?
How could they see if the amount you take the insurance for is really the amount you own?
I could take an insurance for 100.000BTC and than claim I lost my wallet.
How would you verify that this is true and not that I had only 50BTC at the moment I lost my wallet, or that I even lost it.