That's incorrect. Both Elvis and the Beatles sold more. Actually, I think Bing Crosby may have sold more too.
MJ's Thriller was the biggest selling album of all time though. It can be found at any garage sale or thrift store nowadays.
I wonder how many mp3s he's sold. Be interesting to see if anyone actually STILL listens to Thriller. That time period was a time of awful plastic garbage music, and MJ was the king of the heap.