Most people I know that were not 1.0 bought digital copies.
All Legacy and 1.0 (there were a lot) got their 2.0 copy free.
To top that of their numbers from VGchart have notoriously been inaccurate. You also have to look at when those chart numbers were put together.
If that is just pre-order than that is very good.
My guess is after subs start the total will settle to around a million which is about what FFXI had before things shrank after 8 years.

regardless of the number SE was expecting to make a profit just on the numbers they had, They exceeded that by multiple times to the point they had to halt sales.

After about a year look at the number of subscribers that will tell you if it is a success or not. As long as SE continues to make a profit causing them to put out more content regularly then I consider it a success regardless of the number of people.