Power
Not all executives are created equal; your power depends on your position. If you're the CEO of an HMO, you're at the top of the heap, with all the powers and responsibilities that go with that prestigious position. You're responsible for making sure that all of the investors, the providers under your HMO, and the customers under your policy are having their needs met.
If the customers aren't happy, you don't get to be happy either. For example, if a group of customers are complaining that a primary care provider (PCP) at a particular facility under your HMO stinks, you have to address that and, ultimately, decide whether or not your HMO will continue to do business with that facility. Talk about having to be a people-pleaser.
Or maybe you're a COO, where you're more responsible for the day-to-day tasks of the HMO. While the CEO has the power of the overall culture and vision of the HMO, the COO works to make sure the other employees are actually making that vision happen every day. We could go on forever; there are a lot of different executive roles at an HMO, each with a different amount of power over a different section of the company.
The lower on the ladder you are, the less influence you have over what the company does. No matter what your role is, however, you'll have a lot of power over the general public who rely on your HMO for healthcare. You're in some way responsible for the health and well-being of a lot of different people. That's, like, Superman-style power.