Whether or not Medicare-for-All lowers or increases total health care spending in the US is quite irrelevant to average Americans. What matters to them is will paying for M4A cost more than they currently pay for health insurance and out-of-pocket costs.
Needless to say, at this point no one knows what M4A will look like (but certainly not like current Medicare) or how it will be paid for which may be any combination of income taxes, payroll taxes, corporate taxes, a VAT and premiums.
As you can see below, there is no chance only the wealthiest Americans can foot the bill.
Sanders’s office estimates that raising federal tax rates on the wealthiest Americans to 52 percent, and ending favorable tax treatment for capital gains and dividends, would cover just 5 percent of the cost of Medicare-for-all. Source: https://www.benefitspro.com/static/about-us/
Will some Americans come out ahead? Yes, some will, those with high current premiums and high health care expenses before they reach their out-of-pocket limit.
But while most Americans will trade their current premiums and out-of-pocket costs for some new form of taxes, few will save money overall …. because in most years a typical family will have few or no health care bills.