When I talk sales here I am speaking purely in a commercial and marketing context. A game that sells just a couple of million can still be a success in many other ways, including being a "fan favorite." For me, then, AAA success amounts to the sales numbers of games like Skyrim and Witcher 3, 42 M and 35 M respectively. Even games like DA:I and ME3 have sold around 10 M. By contrast, commercially successful AA games like The Outer Worlds 1 have sold around 3 M, and older games like DA:O and ME2 sold around 5 M. And then you have games like D:OS2 and P:Km with sales in the 2+ M range. So this gives me a sense of where the cutoff point may be for sales "success" between a AA game and a AAA game, and that seems to be around 5 M. In other words, if it's a AA game, sales of about 2-3 M would be good and around 5 M would be excellent. Whereas for a AAA game, around 10 M is the low point for being viewed as a success.
But the bottom line is that this is just my personal take. People can see this in whatever way they want. I'm sure there are people out there who will sing the sales success of a game that sold 2 M even while putting down another game that sold 5 M, all because they personally loved the first game and hated the second game. All people are ultimately subjective, myself included.
some numbers need to be updated here: Outer World has sold 4m: https://www.vg247.com/the-outer-worlds-4-million-copies PK has sold 1m after nearly 3 years (so it is far from being in 2+ M and it is not in the same league in terms of sales compared to DOS2 which has reached this number in 2 months) https://gameworldobserver.com/2021/...sold-almost-three-years-after-its-launch and again with some of the Bioware titles (DA: I and ME3) where I really tried to find any source to show if these titles have sold 10M but I really cannot find any except for the source that has been provided here before so I really want to know your source if you can find it. and of course, we have DOS2 which we don't have any source (after 1M) about how successful the game is