Certainly not impossible, but one thing is a disincentive to commit a 51% attack is that if you had that much computing power a more profitable use of it would be to just mine rather than create fake transactions which, if detected, could crash the value of the currency.

> a disincentive to commit a 51% attack...

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.

> if detected

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.

Last I checked it was around 60%. Also, Bitmain is the sole supplier of ASICs to most of the Chinese miners, and thus has some power over what those miners do or don't do (particularly in the Core vs Cash debate).