My FIL never had Medicare coverage even though for many years he paid into SS/Medicare system. As I understand it when he turned 65 he never signed up for Medicare, hence, never started paying the monthly premiums. I assume he never signed up for it as he is a veteran and felt he could always get his health care for free thru the VA. Yes, he has always been really cheap, sometimes to his detriment.
When he finally figured out that Medicare would have been the smart way to go, he would have been required to pay huge monthly premiums to make up for the number of years he did not pay premiums. Of course by then it was no longer an option because he could not afford the cost. Over the years he neglected his health because it is a long distance to the nearest VA clinic and even further to the nearest VA hospital. My opinion is the care/service he received from the VA was inferior to what he would have received locally using Medicare.