So increase the health care spending, then you can raise premiums. An issue the ACA drafters already knew about, and tried (and failed) to deal with.
So which is it? Insurers unfairly denying reimbursement for what should be valid claims, or insurers unfairly increasing spending on claims so they can increase their profits.
Also, go look at 5, 10, and 15 year returns for the big insurers (UNH/Elevance/CVS/Cigna/Humana/Molina/Centene) if you think health insurance is a good business for earning money. Spoiler alert: they’re less than desirable, stick with SP500.