Try steelmanning it. Their argument is that crypto is as worthless as an investment with Bernie Madoff. Therefore, the Netherlands should exit early so its citizens aren’t left holding the bag.
It's basically if you've ever read about MMM[1] and thought: Why didn't the government do anything? That's the kind of thought process they are likely in.
Of course in my opinion Madoff & MMM are fundamentally different than cryptocurrencies[2] because there isn't someone at the top who can hide what is happening or issue new coins. Arguably what is happening with Tether might be similar, but that's a very specific thing that you try to target with government intervention instead of blanket banning.
That’s their claim to argue against.