It doesn't make that much sense tbh.
We know 5E is biggest selling D&D ever but if the 60 million number is accurate they've got around 10 times as many players some previous editions that generated 40% of 5E numbers approx (inflation adjusted).
The other number floating around was 50 million players ever in previous statements.
Hence why 60 million doesn't make much sense.
It's why I suspect they haven't released hard numbers except for cherry picked ones and book scan (which are great numbers btw).