The development time would only make sense if it was a GTAV killer. Even Rockstar had trouble following up on the financial success of GTAV online (people don't like the multiplayer component of the cowboy game). C2077 should have been a smaller game -- it was incredibly ambitious, but the execution of the actual game (the part that is interactive, not the part that involves sitting around listening to audio files while animations play) is less impressive than what you see from some solo devs. It just has lots and lots of art assets, animations, and audio jumbled into a simplistic game that is like many Telltale games glued together.
As it is it seems like they kept remaking the game part endlessly while they had people working on creating tons and tons of assets. This helps to explain why there are dozens of vehicles, but only two quest lines that involve any vehicle gameplay (Delamain Crazy Taxi and the Great Tranny Race). Both of those quests, mind you, have worse gameplay than GTA2, and look really pathetic compared to GTA3. There are lots of great assets -- a bangin' soundtrack, zillions of outfits for random NPCs -- but not much of a game to stitch those assets together. It seems like the studio was working like they were furnishing 3D models and textures for an asset market or as a supporting studio for another studio that was in charge of making the actual game part, sort of like how Ubisoft will have a studio in Indonesia making nothing but grass textures and 3D models of garbage cans, ashtrays, and motorcycles. Then they just had those studios making endless assets piling up in the hopper for years until the main studio rushed through slapping together a half-assed game at the home stretch.