The statement in the May press release/slideshow was that "over 50 million people have played Dungeons & Dragons to date", right? Are we sure they're just counting 5E?
Edit: Right now I'm wishing that I'd read my copy of Game Wizards already and had it handy to check old sales numbers.
Well, if we add up the numbers (and are generous) and say that is 25 million AD&D players over it's lifetime (1e and 2e), 5 million 3e players (that's with several million books sold, and at least close to a million PHB's over 3e and 3.5's lifetime to put that into perspective, with the 5 million commonly tossed around seemingly extracted from a million PHB's sold and multiplying that number by 5..not sure if that was 3e ONLY or if that is inclusive of 3e and 3.5...taking the liberal approach I'd say that is 3e only), 3 million active 4e players, that is 33 million players.
That put's it at 7 million 5e players (a LOT LOWER than many 5e hardcore fans claim) and 7 players per PHB sold on the old number...and when talking about essentials kits and starter kits we could be at a 5 to one sales ratio.
I recall though that there was a claim that there were at least 15 million 5e players at one point, which would put it at 48 million. AT the time I questioned how they were getting their numbers. One of the easiest ways is normally taking the number of PHB's sold and multiply that number by 5. (It doesn't need to just be PHBs, it could also be box sets that have rules for play like D&D's red set, or the Essentials kit...etc...though that makes it a more murky number as there is absolutely overlap in that).
If we look at it as 15 million on the more traditional route that would mean 3 million PHB's sold several years ago. That is still 15 to every PHB sold. That doesn't add up either. We could go with the FAR more murky number of it including Starter Boxes and Essential Boxes (And let's face it, just like the Red Box for D&D, there is a MASSIVE amount of overlap between players buying those and the PHB...but...hey...numbers are numbers). My guess is that they, combine sold at least a million copies (solely a guess on my part), bringing us up to the 7 to one ratio.
At 50 million players that puts it at 17 million 5e players. Plausible...and FAR MORE REALISTIC than saying 25 million 5e players, 40 million 5e players, and especially 50 million 5e players.
It relys on a heavily allowed liberal approach for no overlap between those who bought PHB's, Starter boxes and Essential Kits, and digital...but Plausible.
With that 1 million PHB's sold (probably over that now, but no where close to where they'd need for higher numbers) I could accept somewhere between 15 million to 17 million, but also seeing that it could actually be much lower at the 7-10 million player mark (still, no mean feat, meaning that it is the most played in our modern era since the time of the 80s and double the numbers of almost every other edition). Going by old metrics (if we say 5e sold 1.5 million PHBs by this point and multiply that by 5) it would fall into that range of 7-10 millon players of 5e which makes a LOT more sense.
I'd say 7-10 million is acceptable numbers, 15-17 million are plausible numbers, and anything over that starts getting ridiculous for people to claim regarding how many are actually playing 5e today.
Now, if they are claiming 40-50 million players EVER, or total...I think that could hold. It's only 50 million if we give it a lot of slack and go with the best numbers given for every edition ever. I'd put it more realistically probably at 25 to 40 million players ever, but that probably doesn't roll over well for those who love the PR and Hype machine.