You're assuming a level of good faith in crypto bros that frankly doesn't exist. They aren't interested in any criticism of bitcoin and the like, they personally stand to make money from it and you are just their next potential victim.

I take the dismissive stance you're talking about when dealing with anti-vax, flatearthers, and qanon types. I'm not above that.

Having said that, my original point is the same: then don't engage at all. I don't go posting on flatearther forums how "i won't argue and that their opinion is stupid". I either fully engage and endure what I perceive to be unbelievable stupidity, or don't engage at all.