How essential is curiosity?
A non-answer: curiosity is not the same as "passion for research", if the latter refers to the contemporary commodified version of "research". Exactly as in the question, some clever people see that their "diddlings" could get funding from some funding agency, and "go for it", without really sincerely caring about the issue they pretend to address. Srsly.

"Academe" is a sort of game that is in fact not so wildly different from "business", although its conceits and minor dynamics are different. The major dynamics are self-confidence, ... and bluffing, up to a point. "Bluster", for sure. 

I do think that the individuals who bluff-and-bluster in academe are sometimes less sociopathic than "business people", if, or when, they stay well back from wrecking the pension plans of millions of people. Faint praise, yes.

More directly, I have observed that many people find that their naive, early-life perceptions of any given thing was naive... Special case: academe.

Pro-tip [sic], lotta people who know what they're doing are "not noisy"... that is, do not violently broadcast nonsense. 

I do also seriously think that the question is not "can one be a success in academe without buying into the myth of endless curiosity" (which is the best possible myth), but "will I be able to pay a modest mortgage and have health insurance for my family...?" This is a tougher question, and depends on local social politics. 

Fairy tale: once upon a time, I thought I'd just live till I keeled over at the blackboard... but then there were kids, aging parents, aging spouses, kids-again, ...

"Wait, what was the question?" :)