Why is it that people here can't differentiate between the past and present?
In the past, albums on average sold more copies than they do now and it was much easier to sell 10million then than it is now. Mike selling 10million in 2001 was not a spectacular feat because it wasn't particularly unusual. Now it would be incredibly unlikely for anybody to sell 10million copies in a year, purely because albums just don't sell that many on average. 10million sales in 2001 is possibly the equivalent of selling about 4 - 5 million now, so please stop using sales of Invinible to justify that he could sell 10million albums now. Just look at annual sales figures of the best selling albums of the last few years and you'll see that what I'm saying is true. You're only going to be disappointed when the album sells 4 or 5 million, which actually is fairly successful in todays market. Don't expect 10million!!
BTW, T25 sold less than 3million copies worldwide. Number ones has also sold well under 10million in the 5 / 6 years since release, so I don't see how you justify 15 - 20 million.