Partially, it is hard to "prove the negative" in a way.
The real issue and logical fallacy is people are frontrunning the argument: they are making extraordinary claims of either the current capabilities of the tech or future capabilities, without offering evidence beyond "it's obvious!" or "have you tried it?" or "use the latest model, it's much better!" etc.. and maybe they don't realize it, but these are not good-faith conversations/arguments.
So, you can't respond to these - there really isn't anything to respond to, and the person is not conversing in good faith (they are assuming you're unfamiliar with the tech, they are assuming a bunch of things, really), though I do give them the benefit of the doubt and would say they aren't doing this to be trolls, they're just excited about the tech.
Same with BTC, but BTC had some extra benefits: with BTC it had a "dual use" really, the currency made promises "of course BTC is going to take off, it's obvious!" and the tech made promises "wow, can you imagine the uses of a blockchain!?"
I mean, I had my CTO still saying in 2023 that we should use blockchain tech for a CENTRALIZED platform. Unbelievable!