In the US, insurance company profit margins are capped by law. The insurance companies have to spend at least a certain percentage of their premiums on claims. If they spend less than that, they have to partially refund premiums [0]. So insurance companies are unable to increase their profit percentage by law. The only way for them to increase their profits is if they keep the same percentage by increase the size of the pie. Higher across-the-board healthcare cost benefits insurance companies as much as healthcare providers—if the healthcare costs double, they get to keep 20% of 2X instead of 20% of X.

[0] https://www.nytimes.com/2020/08/05/health/covid-insurance-pr...