I think you might be exaggerating with "immunity" in the post title. Granted, I didn't hear the entire conversation, although it seems that you had a rather open-ended conversation just sharing ideas, and because the kid already had heard of crypto, you weren't fundamentally shaking up his worldview e.g. by explaining inflationary economics.

Many people I know have heard of Bitcoin for years, talked about it several times without immediately "accepting" or "rejecting" the idea, and eventually realise the value proposition over time. I'd call it "immunity" if five years from now after having a few more conversations on the topic, he tells you that he doesn't consider Bitcoin any different from the rest of "crypto".