That's the same game though: if I know a guy who can get me weed or whatever, I will know a guy who can get me bitcoin.
And since there is no physical product or evidence it's actually much easier, my friend from Amsterdam will have a lot of trouble bringing me weed, he will have zero difficulty sending $100 worth of BTC to an address I give him.
The idea that you can just ban things and they will go away should have died with alcohol prohibitions. I guess at least no one will get killed in a war on crypto...
How does your friend from Amsterdam convert his crypto to Euros? The value of crypto more or less relies on there being an off-ramp to local currency. Also he should use Monero!
I assume somewhere on earth exchange will remain legal (eg Amsterdam). So my friend just uses services legal to him locally.
And even if it doesn't, your friendly local drug dealer, who may already be trading crypto to purchase product, will presumably offer exchange services. No one needs an exchange they can just charge a spread between people wanting to buy and those wanting to sell. That's how money change already works after all...
Where does the clean money to exchange for crypto come from if there's no legitimate on-ramp and off-ramp? You could at least exchange drugs and alcohol for dirty fiat.
To make rummy a good metaphor for this discussion, you need to modify the normal $1/point rummy gambling rules; say making gin gives you $1000 bonus from the house or something. (There's a resemblance to quiddich here, I think.) Anyway, now you have the two extreme strategies: knock if you can, which gets you a few dollars each time, or try exclusively for gin, which usually costs you money on each hand but sometimes pays off. If you're skint, the gin strategy won't work since you can't stay in the game long enough. If you're flush, the knock strategy is uninteresting because a few dollars doesn't make a difference.
Now make that bonus $10,000,000,000 and you're making some unicorns, Harry!
Now imagine you only have budget for a single round before being eliminated and some of your opponents have money to keep playing indefinitely. That would be the most accurate metaphor
No one is forcing you to order a frappuccino. You do realize you can get drip coffee (actually pretty good) and espresso drinks without added sugar there, right?