They make deals with hospitals. I don't know the exact nature of the deals, though . But I think they make the bulk of their profit from people who pay for insurance but never or rarely use it.
They are also experts at finding reasons to not pay for meds or treatments. The most infamous is using pre-existing conditions as a means to not pay for treatment.
But they're not allowed to do that now. Or they have been handicapped from doing it like they used to. I honestly haven't looked at the laws for preexisting conditions for a few years so they might have changed.
They make deals with hospitals. I don't know the exact nature of the deals, though . But I think they make the bulk of their profit from people who pay for insurance but never or rarely use it.