Nobody is claiming to be selling stock in companies. They're claiming to be, and are, selling synthetic assets that track that price movements of stock.
But they're absolutely not fraud or "fake stocks".
So if what this is doing isn't any different than a bucket shop... I think we'll see the same outcome.
Of course this doesn't address contracts being written out of Russia or traditional financial havens, but how valuable is a vehicle which can't be used to move assets into or within the US or Europe?
I think the question of enforcement is the wrong one.
Esp for chain running evm compatible contracts that are more scalable than ethereum and can have millions of ephemeral validator nodes.