This is all generally true, but it won't shake out quite this cleanly in reality. People like me, who have quality health insurance subsidized by their employers, will likely see an increase in overall cost of healthcare, which will be balanced out by many less-privileged people seeing a decrease, and sometimes a large one. Also, healthy people who do not currently have health insurance will necessarily be paying more than previously. Of course, they'll then have health insurance, so over time they will come out ahead, but it might be hard to make that clear to them.

I'm not trying to argue against M4A here, but I think leftists and more progressive libs have a tendency to underestimate the scale of the healthcare issue, and I think that breeds skepticism among those we need to get on board with the policy if it's ever going to be enacted. Being upfront about what it will take to make it happen, I think, helps people see a policy proposal as more credible.