Whether Nakamoto is a person or a group is really irrelevant. A game was created and if cashing out is within the defined rules and expectations of the players, then there's no crime.
As to your assertion that widespread adoption necessarily creates unbounded riches for the founders, or even the early adopter, I don't see that as a supportable premise. It's a matter of scale. I can think of several titans of information industry who have benefited disproportionately by virtue of their early positioning. Bing! As well as subterfuge concerning creation or adaptation or simply buying on the cheap their purported innovation. Bing! "Huge portion of the world's wealth.." ??? Seriously? How so?
As to what a government will or won't allow - that's kind of the intention of bitcoin such that arbitrary currency manipulation from sovereign is difficult if not impossible. I hold US currency and by definition I am a speculator. I make the implicit assumption that it will tomorrow have nearly the same value as it does today. Any other action than NOT continuing to hold it is self-destructive if I perceive any negative deviation beyond that 'nearly the same value' approximation. There is no currency, including precious metals like gold, which are guaranteed. Thus, use of any of it is a speculative endeavor.
I think you underestimate the driver for a cryptographic trading platform and currency. Every disruptive event in the world's history has made fortune for a few and has built on the backs of those less well positioned. The fact that an adjustment occurs enhances the adaptability of bitcoin even while it might be a large divestiture. Such events have a finite limit. It is, perhaps, a sign of improving maturity in bitcoin market.
I have no bitcoin and I am not involved in it in any way other than wondering "what if".