The 42-years old musician accepted payment in Bitcoin in 2014 when he had released Animal Ambition, and made about 700 Bitcoins in sales from the album.
He has not cashed in the cryptocurrency, which was going for around $662 per Bitcoin back and is now valued at $10,000 to $12,000 per unit.
This means that he turned $400,000 (from the album money) into $7-8 million through Bitcoin exchange, according to TMZ.
The rap album, Animal Ambition, was the first to be made available via Bitcoin.