Ackman has a very mixed track record and has not had particularly great returns. To believe that he somehow predicted the entire sequence of events is being incredibly generous. Earlier this year he laid out an unbelievably lazy bull case for Netflix when it was around $350/share and said he had accumulated over a billion dollar position only to sell it a month later a massive loss saying the story had changed.
It's not that he tried to predict, it's that he tried to cause a panic selloff to buy stocks for cheaper. I imagine his CNBC interview had some effect it was unhinged and went semi viral.
This is the first time it's occurred to me that any "market-expert" who is widely listened too has an inherent conflict of interest. By misleading the public they can increase their own gains.