Is 25k unrealistic? Pantheon sold way more than that and it’s not even a real game.
Only 2-5% of players in F2P games
ever spend money. And for subscription-based apps in general (not gaming specific), the "install -> paid" conversion rate is often below even 5-10%. So the conversion rates on paid subscribers is actually pretty damn low. In fact, the box price alone will likely dissuade another portion from even trying the game
at all. They'd need to have a box sales rate north of
250-285k+ to generate those kinds of subscriber numbers.
Plus, many MMOs today don't release as "boxed copy + subscription". Instead, they're free-to-play or use other monetization, so sales-figures are often buried or not comparable. When sales numbers
are reported, they often count global units across all editions, multiple platforms, or include pre-orders, which makes comparisons tricky. Most recent "MMOs" with box sales lean into hybrid models (box + early-access + live-service), so it's unclear whether "sold copies" map cleanly to long-term MMO viability.
There isn't really a recent, well-documented example of a brand-new, subscription-based MMO launching in the last few years, selling 250,000+ boxed copies, and still being sustainably active. Most attempts either pivot to F2P, blend in microtransactions, or quietly fade away. DayZ is the only "recent" one you could
maybe call an MMO to have done it. But DayZ has always straddled survival/MMO-lite rather than "classical theme-park MMO". So it doesn't really serve as proof that a modern traditional MMO can still launch and survive at that scale.
Outside that, you're mostly looking at legacy MMOs or games from a different era (when box-sales + subscriptions were common).