I read somewhere that several bitcoin mining facilities in China, when counted together own over 50% of the hashing power currently online in the Bitcoin network. If true, collusion scenarios could easily be imagined.
Consider that if a state goal was to wipe out the wealth of the other 49% as a plausibly deniable economic attack, then having a majority of the mining power within your borders makes a lot of sense.
How people think of that hypothetical if-then scenario depends a lot on numerous factors. I think, in places where corruption is more common, it is easier to believe it's less likely you'll get caught, or minimize the consequences when thinking about it. There's also a lower threshold for your imagination to go wandering off in that direction and begin architecting plans.
"If detected, could crash the whole thing" is a way of thinking more common in cultures where the rule of law is far more established in the common mindset.
I'm not making any sort of prediction (and I own bitcoin myself, though not a large amount). I'm just saying - this is how our minds work.
I know many would disagree with this, but while Bitcoin was the first of its kind, and it absolutely cleared the way for all the subsequent coins, its quickly becoming unusable. And that's not even considering the massive volatility of it. Such volatility implies that proper volumes aren't there to support its value. With that in mind, and also the notion of an aging technology, I think investing in it is not a good idea.