Baby steps. They float this idea to see how it plays. Then they enlist their typical allies to push the idea on the masses (who will support it as many don't have private retirement accounts). Once it is generally accepted as coming to be, they will make the second part, their ultimate goal, known. It will be for the good of the country, for the sick and poor, for the kids and it will be the duty of the greedy rich to share their "good fortune" with the rest of the country.