Disclaimer: I work at SpaceX, albeit as a technician so I'm very far down the corporate ladder, but I feel that may be unduly harsh.
There can certainly be legitimate criticisms around Musk personally, and SpaceX/Tesla in regards to whether they are overhyped relative to competitors or whether they will succeed on delivering what they promise. With that being said, when a company delivers 70k+ cars in a year, even if this is just a tiny percentage of the overall new car market, or a company puts satellites into orbit, I think we've moved beyond "marketing tech demo" status.