The elephant in the room off course is that whilst he may have turned a $20 investment into $xx xxx sounds all good and dandy. As mentoned above by
@xn--v4h.com this does not equate to actual business profit. Basically, if we had to break down his annual renewal costs into a monthly expense. Then his monthly expenses would be over $300 000 per month if he has like 400 000 domains. Now when you start factoring his sales revenue vs his monthly expenses (doesn't even include - Tax, his personal drawings, any staff costs, utilities and any other business expenses he has) Then things look very different.
This is why I have said a few times that I'm sure he gets a highly discounted rate on renewels AND he could even be getting paid/sponsored/funded by a registry to be a marketing engine for the domaining industry. The amount of hype thats created when he tweets about some of his sales is pure marketing gold. It encourages new people to get into the domaining industry and it encourages people who are battling in the domaining industry to keep battling (keep buying) until the get that one or two big sales.
This also leads me to wonder (purely speculation off course)...I am not making any claims, this is just a theory....how valid are these sales? Sure some might be real but how do we know that a certain amount of them are not smoke and mirror sales...purely to drive this marketing engine?