Democratic presidential candidates are sparring over how much to expand Medicare. Should it be Medicare for All, for people over 50 and children, or for all who want it? Does "all" include veterans, Native Americans, and military dependents, all of whom have their own government program? Does it include everybody who happens to be in the country, legally or illegally? Indeed, do the benefits include just what today's Medicare beneficiaries get, or everything the candidates can think of--dental, eyeglasses, hearing aids, mental health and addiction treatment, "sex-change" surgery, etc.? Does it even include long-term care, which the Patient Protection and Affordable Care Act had to discard because it was unaffordable? Who wouldn't want that?
In 1965, a lot of seniors did not want Medicare. They were happy with their private coverage, which nearly half of them had. They did not trust government. To assure the success of "his" program, Pres. Lyndon Johnson took away their private coverage. Insurers could not, under contract law, cancel an individual's policy, say because he or she got sick, but they could cancel everybody's coverage--and they did. This was a precedent for ObamaCare, which outlawed the coverage many people had unless it could meet stringent "grandfather" requirements.
"If you like your plan, you can keep your plan" was an acknowledged "four-Pinocchios" lie. Sen. Elizabeth Warren (D.-Mass.) does not worry about that because she thinks nobody likes insurance. Possibly true, but that does not mean people would choose the government alternative.
With rare exceptions, such as a continuation of policies from employers, seniors do not have and cannot get a private plan that duplicates Medicare coverage. They only can get "Medigap" policies to cover deductibles and things Medicare does not cover.
After a huge percentage of the population got "covered" by the government, did things get better? People did get more treatment. Great advances in medical technology occurred--likely unrelated to Medicare. However, toxic, unrelenting cost-price inflation began abruptly after 1965 for the first time in 90 years, leading to massive government interventions to put a lid on them. Administrative demands burgeoned--there now are at least 10 times as many administrators as doctors. Then government eroded the value of people's savings by inflating the dollar. If you had put $10 in a mattress in 1965, it would be worth $1.24 today.
Did evil, greedy...