As a former CM for KSP1 and self proclaimed industry professional, you are clearly and directly drawing conclusions based on at best incomplete data. Game sells on Steam, Epic and direct, you only account for Steam sales. KSP is and always will be a super niche game which will not ever have broad mainstream appeal and the studio as well as Take 2 will know this. I would not be surprised a lot of people bought direct.
I'd say the steam numbers alone shows a niche game shortly after EA doing pretty good for what it is, despite the noise which will always happen. My personal take on this is that it is not unlikely at least a part of the noise is due to factors these people are not telling us, for instance them running the game on a Linux platform or older hardware. KSP2 is clearly designed for the future and doe snot cater to 5+ year old hardware all that much , which IMO is perfectly fine when the studio/publisher is in it for the long haul.
If anyone makes the argument the game really is not ready for the main stage, even when labelled as "early access" I would not disagree but here we are. In general though, it would seem that the foundation of the game is solid, which is very important and I'm not all that concerned about the current state. How quickly these issue get addressed and patches released with consistent progress in quality and performance is what will tell us how well the team is doing more than anything else.
If the scenario now is that the devs go silent for a week or two while they work on fixes and then release a big patch, I'm good with that. It is what eventually turned around NMS, which had a far more disastrous launch and is doing just fine, if not really well, now.