Richard Sherman is a visionary ... he was accepting Bitcoin on his website back in 2012 and 2013 -- but there's just one problem ... HE CONVERTED IT ALL TO CASH BEFORE IT EXPLODED!!! NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO!!!!!!!!!!!!!!!!!!!!!! It's a true story ... the NFL superstar tells TMZ Sports he's been a fan of cryptocurrency for years and believes it's eventually going to be the standard way people pay for things like groceries and clothes.