These are all legit concerns, I don't dispute that.
I have very good healthcare myself, 70% employer provided. And the quality of care if we ever went to m4a (that's still long time away no matter who's potus, let's be honest) is a concern.
But, I mean, insurance is still a PITA (I have two kids, so I'm guaranteed to hit the OOP max and deal with all the stupid prescription pricing, aka, find out what it costs after you pick it up). I can afford it, luckily. Other's mileage may vary.
To me, aside from the overall well being of everyone, the most intriguing benefit is taking the onus off of employers/employment. Talk about freeing up the workforce to change jobs, test the waters, start their own business, whatever. Game changer. It works everywhere else, so I'm more than willing to give it a go. Biggest drawback, as always (and my main agreement with naysayers), is our gov't is run by a bunch of clowns. So they'll probably fvck it up.