The ACA requires the somewhat perversely called Medical Loss Ratio (MLR) to be at least 80% (and 85% for large group plans). The MLR is the percentage of revenues from insurance premiums that are being used on actual healthcare benefits (and thus can't go towards profits, hence the name). Corporate helicopters don't increase the MLR and reduce profits.

This is a perverse incentive. If I'm running an insurance company and my goal is to maximize absolute profit, how do I do that when my profit margin is capped by law in this manner?

Well, I certainly don't have an incentive to reduce healthcare costs; quite the opposite. 20% of a larger cost leaves me with more profit, and most of my customers won't drop my service. It's required by law and subsidized in a lot of cases.

This is why there are marketplaces where you have to compete against other insurers. And companies in particular will evaluate their group plans critically.

No. The ACA's profit cap (the "80/20 rule") requires that at least 80% of premiums taken in must be spent on actual medical care costs.

Only if that's deductible.

I assume you mean in a sarcastic way. If not:

Of course it is. That’s what our man in congress is for.