They are not large but I don’t think that’s quite correct. 100,000 has been the stated number of subscribers on the website for as long as I have been a Roon user (2020) but in February 2021 Danny wrote 250K:
and I think I saw a later post in reply to someone quoting these 250K that it was much more by that time.
Even if it had just 100,000 annual subscribers (excluding lifers), 12.5 per month x 12 = 150, and 150 x 100,000 = 15,000,000, not 4,000,000