The reason golfer use those markers instead of coins is that if your ball is between my ball & the hole using a coin when you putt the coin because of the raised edge could knock the putt of line where as a marker when preesed into the turf lies flat with the grass giving a perfect putting line to the hole.
And there is your answer. Fore.
P.S. I will give you 2 x $1. Star City Casino chips for that ball marker Dave.