Ok, first off I agree that forcing someone to buy insurance as a condition of gun ownership is probably unconstitutional and all the other things that have been said about it above.
Second - liability insurance. If you are not carrying some sort of umbrella liability policy you are probably underinsured and leaving your estate at risk. And no, I don't sell insurance. Most insurance agents will not tell you about liability policies because they are a low profit product that require a fair bit of work on the agent's part. Normally you have to have either auto or homeowner's policies with the company to get a liability policy. They may require that you up the limits on your auto policy especially if you have the minimum required by your state. Mine requires 300,000/500,000 medical/personal injury. The difference in cost between that and the minimum is very small.
A liability policy kicks in if any one comes after you because they are injured on your property or by your vehicle. The theory is, if you run a stop sign and injure someone they will probably sue. Their laywer will look at what you own, look at the liability policy and tell their client " We can get 5 million if we win but it will take 3-5 years in court or we can settle for 1 million (or whatever your policy is) and get paid next month."
I don't know what it would cost in New York but in Florida my $1.5 million policy costs abot $425 a year and covers three rental houses, my primary residence and all my vehicles. Yes it's a lost cost if you never use it. The alternative is losing everything you have if you need it and don't have it.