Just because Elon might have invested in a few ai companies does not make him exceptionally knowledgeable about the future of AI. He might know slightly more than the average person, as things will have been explained to him in layman's terms, but intelligence wise he is not the one putting the technical work in to advance the technology. If you're talking a hundred years down the line, sure AI might be heading that direction, but right now it is just nibbling away at certain work sectors and is demonstrating flaws such as a bias it might have picked up from all the stuff it has ingested. Elon loves to pretend he is an expert in many fields, but is quite fickle and has cursory information that he tries to project into higher meaning.
You might not like or trust Musk and that's fine, but what he says is no different from what actual experts on the matter say. I challenge you to find a single expert who actually has some expertise in the development of AI (and automation) who would claim that human labour is irreplaceable. Maybe you could find a few of such a decade ago, but nowadays most agree that pretty much every area of work will get replaced eventually.
And given that progress happens exponentially, saying that we need another 100 years for this to become a problem is a massive downplay. Sure, there always be *some* jobs left, but if you can't have a functioning society where the majority of people have nothing to do.