Most of the derision I see for both of these companies takes the form of standard investment analysis for established firms, or simple hatred on ideological grounds. Tesla and SpaceX are like Apple when it was Jobs & Woz in their garage.
Orbital data centers, moon and asteroid mining, more launches, by two orders of magnitude, than any other commercial entity on the planet... SpaceX is going bigger. Yes they might go bust, but evaluating them as though they were Microsoft, GE, or Samsung just doesn't make a lot of sense yet.
Remember when Jobs of Apple died?
Now think about what is going to happen when Musk dies. Compare and contrast.