The expectation for them wasn't to sell 8 million Pre-Orders based on a few pretty Trailers and then yell "Psyche!", but to outdo The Witcher 3 that went on to top 50 million lifetime Sales with a genre-defining product that will herald the next decade of "Gaming" and be talked about as an example years from now and that they'll transition to a "Gaming as a Service" model like GTA V Online, which is why their market value cratered after release: https://www.pcgamesn.com/the-witcher/series-salesThe game sold at least 8 million preorders that we know about, to say nothing of day 1 sales. It's already made about half a billion dollars, and could possibly beat GTA for best pre-order/first day sale combination (IIRC they made like $800 million). Whatever a person may think of the game, it is not a failure in any business sense of the word. They could stop everything now and still come out on top.
The Witcher 3 didn't top 50 million, that was the entire Witcher Franchise. I mean, TW3 did sell well. But they're a long ways away from GTAV (something like 135 million sales of that title alone; the entire GTA franchise is upwards of 200 million copies).
As far as topping The Witcher 3 (28 million sold) they have a shot. I would hazard a guess that between pre-orders and first-day sales, they're at least at 12 million, maybe in the 16-20 million range -- there are some sources we don't get data for, I believe these numbers are not counting the Epic store or Stadia but I'm not sure. Factor in the eventual release of an upgraded version for next gen consoles, and I could see them clearing 28 million easily.