But why does this make research on quantum cryptography worthless? Building a system that delivers the full promise of quantum encryption and addresses the weak

But why does this make research on quantum cryptography worthless? Building a system that delivers the full promise of quantum encryption and addresses the weaknesses of the system is the very goal of such research. Classical encryption schemes would never have gotten to the point they are today without this kind of research funding, so why don't we grant this to quantum cryptography as well? And if the method is so fundamentally flawed as some people want to make us believe, why are several dozen research organizations around the world pursuing it? And why is it a bad thing to talk about applications that seem far-fetched today, like "quantum credit cards"? Blockchain-based currencies were probably also a pretty far-fetched concept 20 years ago, but today they have a fixed place in the currency eco-system.