The ACA exchange model is large risk pools with community rating. They implicitly cross subsidize the sick. So if the basic income is large enough to pay for an

The ACA exchange model is large risk pools with community rating. They implicitly cross subsidize the sick. So if the basic income is large enough to pay for an exchange policy without additional subsidies then you've replaced Medicare and Medicaid. However, a basic income of $12,000 is far away from that number at least for an individual. ACA subsidies the purchase of insurance at up to 400% of the poverty line. As for social security, politically I agree that a basic income that was lower than when many were expecting would be a non-starter. However I don't agree that it would fail a social insurance scheme. The social insurance aspect of social security is preventing elder poverty, a universal basic income does that by preventing all poverty. The regressive formula for calculating social security benefits was a canny political move (making it look more like a pension) but it isn't necessary to its social insurance function.