Flying without FAA medical or insurance

Last year, an acquaintance of mine turned 85 and stopped flying and sold his
airplane. He just figured that he had done it long enough and he wasn't as
sharp as he used to be. He flew a lot right up until he sold his plane and
he was quite experienced. I suspect for private reasons that he had not
passed an FAA physical in years and that he did not bother to buy insurance,
since the company would refuse to pay anyway if he smashed up the airplane
without a valid physical.

So... I'd like to throw out two questions to this group ...

1) If you can't pass a physical or you don't feel like getting a license and
you feel like flying anyway and you are willing to accept the liability
personally without any insurance, exactly what's to stop you from taking
this path?

2) How many pilots do you think are doing just this? From reading the FAA
accident reports, I suspect it's more than a few.

I welcome your opinions. Don't bother with preachy, holier-than-thou
platitudes - just the pros and cons.

DB