Earlier quoted context omitted.
Obamacare banned declining coverage for pre-existing conditions and allowed Since they don't see things getting better for them as they get older, maybe it's not so irrational to support expansion of Medicare and Social Security. It's not as illogical or against their self-interest as you think.
Except that you skip over the most important provisions. Do you think that insurance for a 60 year old is 3x as expensive as a 30 year old for health care? The government MANDATES that to be the case. Who do you think pays for that? Obamacare mandates that a 64 year old get charged no more that 3x a 27 year old.
Employers. Or the government - via subsidies. And the insureds themselves.
Have you considered that many millennials are OK with paying more if it means everyone is taken care of? People don't always vote for policies that benefit solely themselves.