Is Bitcoin still an easy to manipulate these days after the many years of exposure to market realities, FUDS, hypes, severe criticisms and the likes?
Technical analysts would usually say, "that crash was coming anyway" and "the bad news was just a catalyst." The existing bear market condition (strong supply, weak demand) was the true underlying factor driving the decline. Another way of looking at this: if markets crash on bad news, it's confirmation you are in a bear market.
In other words, would-be sellers were looking for any reason to sell. It didn't have to be a story about quantum computers that did it; it could simply have been price falling below key stop loss levels. Once the selloff was triggered, a typical price feedback loop developed: lower prices squeezed holders into cutting losses, which begot lower prices. Rinse/repeat.
This is also why bad news can never keep a lid on strong bull markets. Any losses are quickly regained because investors are too bullish to care. If this "quantum supremacy" news came out in fall 2017, the market wouldn't have given a shit.
In today's world, its probably common for traders, banks and elites to have relationships with media. I think it was CNBC's Mad Money host Jim Cramer who admitted he worked in conjunction with journalists to trade profitably. Cramer would buy stocks. Then he would have his journalist contacts publish positive content on the stock he purchased, which would drive the price of his holdings upwards to a sell position. That's the basic format for insider trading determining the degree to which markets are manipulated in this day and age. This precedent goes back literally decades, which means by this point its likely been greatly expanded upon.
News stories are by far the largest influence on market and stock prices. If anyone recalls all of the stock prices that increased dramatically after releasing news of them announcing dubious blockchain or cryptocurrency proposals.
This is one reason why AI trading is likely to never amount to anything. Developers of AI trading software could trade using their product. Instead they choose to sell it to the public, which greatly reduces the effectiveness of trading software on the basis of greater market saturation. While AI software can analyze market mechanics within a technical analysis paradigm, they can't necessarily predict future news stories which constitute the most significant variable influencing market valuation. This negative trend has a tendency to make AI trading bots ineffective.