Insurance works by pooling together every policyholder’s premium fees. These fees are then stored as a reserve in the event of a claim being made. So, claims and losses are taken from this pool and used to reimburse policyholders claiming from their insurers. The contributions of the many fund the losses of the few!
The cost of claims increasing means that the pool needs to be bigger. This, in turn, increases the size of the premiums paid by policyholders.