You will also reduce all sorts of other costs, many of which would be otherwise put on the government's tab.
A major reason for bankruptcies in the US is because of medical issues. You have a health problem, which can result in a lost job, which leads to lost health insurance, which can result in bankruptcies and unpaid medical costs that, in turn, drive up hospital costs. You also have the bankrupt people more likely to collect safety net services like TANF, SNAP, disability and so forth.
And FYI, emergency room rates did fall in MA, though it is not clear that it's a direct result of Romneycare:
Emergency Department Visits Down For First Time Since Health Reform, Survey Finds | CommonHealth
At a minimum, Romneycare has certainly not devastated health care in MA, or the state's economy.
Obamacare is certainly a much better for the insurance companies than a single-payer system.
However, unless they are seriously cooking the books (which is possible), their net profit margin is a reasonable 3.7%
Industry Browser - Healthcare - Health Care Plans Industry - Company List and has been in that range for at least a few years now. (In comparison, soft drink companies have an 11% net profit margin; Coca-Cola's margins are over 20%.)
Obamacare does throw insurers a large number of customers. However, insurers will also be expected to pay out a great deal more, since they can no longer deny pre-existing conditions, and yes, have to rebate revenues that used to go straight to the bottom line.
I.e. If their margins do go through the roof for the next few years, we'll see it. And can adjust aspects like the rebates, as required.
The benefits of Obamacare will almost certainly be less than its proponents insist, and its problems will almost certainly be nowhere near as bad as its detractors insist.
