I think you misunderstand my question.
In a perfect world, you'd keep 100% of the premiums and never pay a cent to a healthcare provider because everyone is healthy, right?
In a terrible world, every single one of your insured has a chronic, long-term expensive to treat condition that requires you to pay tons of money to providers.
In the first/perfect case, premiums are zero, right? In the second/terrible/worst case, you're not making zero money because your (collected premiums - minimum payout) > 0.
See where I'm going with this? In a world with healthy people, there is little need for health insurance and spending trends towards zero. There isn't a need for an insurer. Your company can only exist in a world with sick people.