I'm with ya. Of course, the first and best way to communicate the value of keto is to lose a bunch of weight and keep it off. Having done that, I've had people who secretly want to lose weight, who have noticed the lasting change in me, ask me about keto. They're typically more receptive.
If it's someone on the outside, just judging you according to their outdated mental model of what "healthy food" is, the only thing I can do is challenge that mental model -- everything from "fat makes you fat" to "breakfast is the most important meal of the day!" (coined by a cereal company, of course) -- as diplomatically as possible. That's fairly easy for me, because I'm knowledgeable on the subject and can articulate myself well enough that I at least sound like I know what I'm talking about. I imagine it's harder for others, potentially to the point of not being worth the effort. But because I can, and I think it's important, I will.