There is a stronger argument against crypto: the main use case (outside speculation) seems to be illegal activities. If what you are doing is legal, why not use government currency? If what you are doing is illegal, crypto is great. A currency outside the control of the government (police) is almost by definition made for illegal activities.
In some countries, illegal activities are morally correct, though. Crypto helps here.
But crypto has enabled entirely new types of crimes that did not exist before: ransomware.
I have not completely for or against crypto. I am responding to your comment that people are dismissing because it seems like speculation only. I don't think that is true and that there are better reasons for dismissal?