They keep the 20% that they don't pay out... what they do pay out, they get the invested fraction of, which is less than than what they paid out.

Even if they only get to keep up to 20%, doesn't mean they will pay a dime of what they can get away with not paying.

Because they make more by not paying than by paying... When the payouts are larger, they raise premiums, make money on both sides.

Not to mention, if they can delay payment for a month, that's a month worth of interest on the money in an interest bearing account.

It's largely a side effect of a couple things... first the ACA (ObamaCare) limited the percentage of profit that insurance and medical providers can make... so they instead just grow the pie larger by inflating everything. Second is that they are allowed to have effectively vertical monopoly investments controlling multiple layers of healthcare as a whole from insurance, providers, pharma and pharmacies.

Trust busting and multiple supply lines really need to be established in order to have a chance at restoring normalcy. Which is all but impossible as Pharma alone is the single biggest spender of advertising alone, let alone policy influence over politicians.