Except for the "not making enough money from it" reason. If you do a quick Google search you'll come across quite a number of articles from the past year or so with direct quotes from game developer company executives saying there's not enough money to be made from single player games anymore. inXile itself has said (in a recent Brian Fargo interview) that their next new game (after Wasteland 3) will be multiplayer (and consoles) focused.
They've been saying that since the late nineties and yet we still have singleplayer games. Hell, Witcher, PoE1, Wasteland 2, Fallout 4 (the ENTIRE Bethesda catalogue now and in the future*), HBS' catalogue (Battletech has an MP component, but it doesn't take priority over the robust main campaign), Total War series, Paradox games... That claim doesn't survive confrontation with reality.
It's understandable that games that don't require you to dive into deep lore and riveting stories are more popular than those that do. Some games focus on the gameplay experience and that's perfectly fine. They have much bigger audiences specifically because they're easy to pick up, enjoy, and then drop when you need to do something else. This was the case for, what, two decades now?
Despite that we still get quality SP games. In the same way that burger joints did not wipe out regular restaurants, MP won't wipe out SP.