It doesn't matter whether your counterparty for your insurance is a collective or a single individual like Warren Buffett.
The 'collective' part is a distraction when trying to understand insurance.
Similar for insurance to work you don't need to have a group of people who are in the same situation as you: in principle an insurer can work out the risks, even if you are in a unique situation.
It's just that working these things out costs time and money, so it's cheaper for you, if you are like everyone else.
But eg if you are a famous singer, you can insure your voice just fine. Companies also regularly purchase insurance against customers winning prizes. See https://en.wikipedia.org/wiki/Prize_indemnity_insurance
