Here's the math:

125 million households in U.S.   times $12,000/yr for major medical policy will cost taxpayers $1,500,000,000,000 per year.   

That is 1.5 trillion dollars per year.   

That is just for a weak major medical policy with likely $10,000 deductible per year.   

All doctor visits and meds would be paid out of pocket until the deductible is met.   

You say many households are already insured by individuals or company benefits.    That is not fair.   If anyone get's free stuff everyone should get free stuff.   .   In the long run, individuals will find ways to get on the Government benefit and companies will cut out the corporate health care benefit.   

An important side effect of Government provided health care will be lifestyle policies controlling our behaviour to force us to be healthier.   Eventually, quotas will have to be established for the chronically ill.   Once they use up their quota that will have to suffer and die.   

We simply cannot afford to be sick.