I'm sure Yates made some decent money from the supplement company he was attached to for years. Look at how much other pros get from endorsement deals and Dorian had been with CPN or whatever for a long ass time. He sold the company so it had to of been profitable.
On a side note I was surprised how much size Dorian has kept from watching Dugdale's DVD. He was demonstrating proper form with Mark's working weight and was moving it around like it was his warm up set or something.