I don't really see how that's possible. They are prevented by law from charging more than 25% on top of what they pay out to medical providers. The problem is the providers who are represented by the AMA.
This relies entirely on market concentration and doesn't even bother to address the legal cap on premiums enacted in the ACA. I expected it to be trash because it is written by people who have every incentive to try to blame insurance companies and I was correct.