I don't think anyone seriously believes that the Chinese aren't capable, it's more like people believe no matter what happens, USA will still dominate in "high tech" fields. A variant of "American Exceptionalism" so to speak.

This is kinda reflected in the stock market, where the AI stocks are surging to new heights every day, yet their Chinese equivalents are relatively lagging behind in stock price, which suggests that investors are betting heavily on the US companies to "win" this "AI race" (if there's any gains to be made by winning).

Also, in the past couple years (or maybe a couple decades), there had also been a lot of crap talk about how China has to democratize and free up their markets in order to be competitive with the other first world countries, together with a bunch of "doomsday" predictions for authoritarianism in China. This narrative has completely lost any credibility, but the sentiment dies slowly...