I can't speak for him but as far as it being a waste of time I think the point may be that crypto doesn't produce anything. It has no output. It is literally an investment instrument that's not tied to any valuable asset so it doesn't have any natural value on its own, like, say, diamonds, gold or other precious metals/minerals. It's just space on hard drives in data centers. And it's got a relatively gigantic carbon footprint.
Yes, I know they're working on addressing that but even if they do address it how are they going to address the lack of fundamental value in the product itself. We used to joke about "vaporware" but we've now arrived in a place where CPU processing cycles are now a form of currency?
Color me skeptical. I see a gigantic correction in the future, just like what happened with the World Wide Web in 2000, when all these people literally throwing billions of dollars at internet startups had their financial intestines ripped out through their asses when the bubble popped and everyone realized they had invested in....wait for it....vaporware. Websites with literally no business plans other than "make a website." 10's of billions of dollars in wealth completely evaporated in about a week and we went into recession.
Crypto will eventually trigger a similar reaction because the "product" is completely worthless 1's and 0's on a hard drive somewhere in a data center in East Bumfuck, Iowa.