This is a weird and easily disprovable objection. The numbers are not as high as the scammers for sure, but there are a not-insignificant amount of people using crypto to move real money for its exact intended purposes today.
You know what is also good for crime? Dollars! Everyone takes then. Even worse they are harder to trace. Do you see anyone wanting to ban the dollar or claim that it's good for crime?
When you say stuff like real, non-illegal you close the door to conversation.
With crypto you can exchange money with anyone in the world without an intermediary. Visa/Mastercard cannot ban you. This in itself is huge (most people think about this as an abstract problem that has low likelihood until it happens). There are no borders, there is no censorship.
Sex work? Nope. The powers to be decided that's not allowed. Remember when OF wanted to ban all explicit content?
MJ? Legal in a lot of places at state level. But you can only buy it with cash. Think about that for a sec: you're allowed by the local laws to do something buy you cannot do it.
Does giving money to support people/orgs in underdeveloped countries that cannot afford to use the normal banking channels count as use case?
Do you know what happened in Venezuela recently when their currency crashed and how the managed to stay afloat somehow?
Do you understand inflation and how what is currently happening is just another form of taxation? Is inflation and central bank policies doomimg an economy a real use case?
Have you heard about civil asset forfeiture? Abstract af until something like this happens to you. Is that a real use case?
