Without society it's pretty hard to be well off in the first place. The entire concept of property becomes pretty meaningless without some very basic concepts of a legal system and territorial integrity. Without that you can only own what you can physically defend.

Wealthy people and large companies do generally employ security, but that is merely supplemental. They enjoy the backdrop of a society where the vast majority of people at least recognize the basic concept of ownership, and where protection from external state actors is provided. More to the point, they live in a system where most people see negative expected return from just killing them and taking their stuff

Abstractions like insurance further require a system where agreements can be made and mostly enforced, and where the need for the insurance is low enough for the premium to be workable.

The small security team at any given company is there to handle the the exceptions that don't conform to the larger society's rules. It doesn't replace that protection entirely. You'd need a standing army for that, and you'd have to work full time just to maintain its loyalty.

Even with no direct services whatsoever, people benefit from society in more or less direct proportion to their wealth -- and arguably the benefit accrues exponentially as wealth increases, given that this enables the exponential growth of capital.