It's a dismissal out of hand. As someone with an economics background, you can take their habit in stride by seeing it as a useful heuristic that allows them to keep their eyes on their own ball.

In the real world, we rely on those heuristics all the time - particularly so in this specialists' age. Case in point: the banks. If I really wanted to know The Truth about the '08 crisis, I'd be going down a rabbit hole filled with such delights as "statistical arbitrage," "misuse of the Gaussian copula function," the eternal duality of "stingy lenders" vs. "predatory lenders," the precise role of the government in all this, the role and limit of the affirmative-action regime in tilting the balance towards "predatory," the extent to which top management was motivated by greed versus plain folly, the extent to which top management were bamboozled by a bunch of statistics-Ph.D hotshots whose huge huge returns were built on recklessness, the real reason why there were virtually no indictments, the extent to which the bailout were justified by the big banks "pre-paying" via shovelling huge huge dollar amounts into the U.S. treasury via corporate income taxes, and so on.

And at the end of this laborious and time-consuming trip through Big Bank Wonderland, I'd have...a monograph. A monograph fit for a relevant academic journal, which would prolly be unread in full. Unless I'm an academic in the relevant specialty hungering for a publication credit, all I'll get out of all that time spent is some "inside-baseball" knowledge which few people would be interested in.

How much easier it is for me to say "the banks were greedy" or "what else can you expect from crony capitalism"! Doing so closes my mind to The Truth, but it allows me to keep my eye on my own ball. It also saves me a large amount of time & intellectual labour.

So-called "Bitcoin maximalists" economize in a similar way. They stick to Bitcoin and dismiss all altcoins out of hand because doing so economizes their time and enables them to keep their eyes on their own ball. In a very real way, a closed mind is a time-saving and focus-economizing heuristic that's very useful in this specialists' age.