So, I checked out the new Hanteo feature wherein we can see the physical record index when considering the price of every albums sold. I can't help but notice the gap and difference compared to the rest of the albums listed below it.
This list is for the month of June.
So, I did some math and came to the conclusion that it had a huge potential to reached 10M copies at a minimum if we consider WW sales at the end of the year.
Let's use the second album as an example;
988,204.06 x 10.468 = 10,344,520
(#2 album record index x the formula = Proof's record index for the month of June)
760,157 x 10.468 = 7,957,323
(#2 album sales x the formula = Proof's album sales based on Hanteo's record index for the month of June)
Note: The formula is the index gap between the second and first album, then I used it to get the Proof's 'supposed' album sales in Hanteo if it was released at the same price as the second album.