Yes, I do know what I am talking about. You are right, Medicare has co-pays and coinsurance, and they can be expensive. My guess is that you purchased a Medicare Advantage plan that has deductibles, co-pays, and coinsurance. You can almost eliminate those costs with a good Supplemental (Medigap) plan. I also think that you did not really need your health insurance before Medicare and never really had to use it for anything serious.
Medicare for All (M4A), as proposed in H.R. 1976, eliminates out-of-pocket costs (deductibles, co-pays, and coinsurance) so it would be free at the point of service. Premiums would also be eliminated. M4A would be paid for with taxes. More than 90 percent of households would be would save money and the increase in taxes would be less, sometimes substantially less, than what they currently pay in premiums and out-of-pocket costs.
We gave you an atomic bomb, what do you want, mermaids? -- I. I. Rabi to the Atomic Energy Commission