If you actually trace the cashflows, the "people lining their own pockets with the savings" are mainly not the insurers but rather the executives and shareholders for other large companies with self-funded employee health plans. Most insurance companies no longer provide much real insurance but rather primarily administer health plans on behalf of self-funded employers. Due to the minimum medical loss ratio rule, insurers actually make more profit the more claims they approve.

https://www.cms.gov/marketplace/private-health-insurance/med...

If employers wanted it, insurers would be happy to offer health plans that fully paid every claim with zero denials. This would be enormously profitable for the insurers because they could run those health plans with minimal work. But instead, most employers are constantly looking for ways to cut employee health benefit costs. This means incentives aren't aligned.