The reason why westiods keep pumping out China collapse theory is because it makes them feel better about themselves. The West's entire culture is based around being the pinnacle of human civilization, the "End of History", Dominant race , etc. So seeing non-westerners succeed is fundamentally offensive to their world view. Even "left" wing westerners can't let go of their chauvinism, and feel the need to lecture or dismiss the "lesser" countries/peoples socialist movements. Until the current global order crumbles, they will remain this way.
You can see this even in writings from several centuries ago. Even when Europeans were conceding Chinese skill and quality in things like porcelain or admiring the idea of civil service selecting based on merit, there would still be some grasping at straws to try and still be superior like (paraphrasing) "But they are idolatrous heathens and we worship the One True God so we are still superior despite them being better in just about everything else". That was before the weakness and corruption of the late Qing made them sneer and not even concede anything at all.