Before the Affordable Care Act, health insurance companies operated in a state of monopolistic competition, in which competition over prices and services was constrained by the fact that it is difficult for people to change their insurance provider. Since most health insurance was (and still is) provided through employers, many...
Before the Affordable Care Act, health insurance companies operated in a state of monopolistic competition, in which competition over prices and services was constrained by the fact that it is difficult for people to change their insurance provider. Since most health insurance was (and still is) provided through employers, many people can't really change their insurance without changing their jobs. As a result, their health insurance company has a quasi-monopoly, and like any monopoly can charge higher prices, provide worse services, and above all reap higher profits.
The healthcare reforms proposed by Obama which eventually culminated in the Affordable Care Act were designed to increase competition in the health insurance market, by creating exchanges where people could easily compare and choose different insurance providers, and originally even by offering a "public option" in which people could purchase healthcare coverage from the government if they so desired. Obama also argued for mandatory coverage of pre-existing conditions, which required instituting tax penalties for not having insurance (otherwise people would simply wait to buy insurance until they needed it---and that basically defeats the purpose of insurance).
This was fiercely opposed by the health insurance lobby, because they knew that this increased competition---and especially the option of escaping for-profit insurance entirely---would force them to lower prices and improve services, and thus reduce their profits. They were all in favor of the individual mandate, but opposed the language on pre-existing conditions (even though that was the only reason the individual mandate was included in the first place).
The insurance lobby was unable to stop the Affordable Care Act entirely, but they did manage to weaken it substantially. The public option was dropped, the exchanges were limited (and managed by the states, many of them with Republican governors and legislatures hostile to the whole reform project), and the expensive and inefficient Medicare Advantage system was expanded and protected instead of being removed as it should have been. Fortunately, the inclusion of people with pre-existing conditions was retained, and that itself is a major victory for healthcare reform.
Apparently the insurance lobby succeeded in getting enough of what they wanted that they are now lobbying to retain the Affordable Care Act instead of continuing to reform toward something better. Also, their profits are higher than ever.