That's not that surprising because the margins on insurance plans aren't all that high. The percentage of each dollar of premium how much insurance companies ha

That's not that surprising because the margins on insurance plans aren't all that high. The percentage of each dollar of premium how much insurance companies have to spend on medical care (aka "loss ratio") is mandated to be at least 85%. Relatively small percentage changes in the premium they bring in can make them go from being the most profitable plans they have to not being worth having at all. (This is generally true across the insurance industry: you can see other examples of companies pulling out because of relatively small changes with home insurance companies leaving California and Washington)