Probably both sides can convince themselves the tech does or doesn't totally obviously beyond a doubt work (to differing definitions of "work"). But predicting public adoption and widespread use (which makes most things more inherently useful too) isn't easy for anyone.
People who can’t see or imagine use cases become sceptics.
But others who piece together enough observations to tell themselves stories of why it will work become believers.
But neither can explain why the tech will or won’t work, so we end up with technobabblers and angry sceptics.