Wheel flew off car...now who is at fault?

ive had 2 wheels come off in 40 yrs.....one sounded funny i stopped and saw the lug nuts were gone...took 1 off other wheels and got to parts store for new ones.....other the wheel came off at 50 mph and went by me.....i got it and put it on and sold it...seemed ok.......good luck..now i check them every month and listen more...your not likely to get anything from repair shop after 17 days...and didn't you hear/feel anything????