Ruin Explorer
Legend
WotC also said D&D Beyond had 10 million registered users at the time they bought it.This is a way of finding. WotC claims there are 60 millions of D&D players.
Roll20 claims to have 10 millions accounts, and in their report posted here, a little over half plays 5e. That's 5 millions for roll20. But that's accounts ever created, not players, so that's the high-end estimate.
Fantasy grounds published in their report that they had 95,000 sessions in January 2021 (a little old, I know). In the "best case" they were all active users who play once a month, so there is no duplicate. That's, assuming 6 players per session, a little under one million.
I don't know the relative market share of VTT but those heavyweight are still dwarfed by the general 5e market.
I concur.
Those are relatively high-value as well because you can only register with Twitch, Google, or Apple accounts (and Twitch is now deprecated I believe).