Re: Worst argument ever
Is it not the case that though it is much harder to buy 'illegal' stuff with money (particularly electronically as traceability etc. It has to come from an account that you 'usually' need to provide ID to open)
The guns argument is a bit of a strawman as most guns that cause death in 'Murica™ are legally owned. It is just the retarded nature that they are allowed to be owned.
It is generally more difficult to get hold of illegal stuff with cash as you have to actually hand it over in person to receive the goods I don't think that major drug purchases are done by post - for a start, the postal cost for a briefcase of money would be pretty high! whereas crypto is just a click of a mouse with zero traceability.
So whilst, not an amazing argument, it is not the 'worst argument ever'