Earlier quoted context omitted.
I didn't say that any of the M4A plans would ban private insurance. That doesn't change the fact that Bernie has stated that his M4A plan would, even where the plan he's put forward doesn't show that. I think it's fair (if a bit naive) to take politicians at their word on occasion. Moreover, I think it's more than a bit disingenuous to assert that plans that are disallowed by law from competing with Medicare services…
Your analogy is false, though. A more correct one would be "Netflix is allowed to show all initial movies in a franchise, but sequels are fair game to anyone." Do you understand the difference between primary and secondary / supplemental insurance coverage?
Again, I'm not making the claim that it's what's in the policy, but it's what Bernie has said, and others have echoed. Reasonable people can disagree on what policies are practicable or likely, but if you're a person who believes their health insurance might change based on those statements, then it seems like a warranted fear.