That’s an unnecessarily rude response. Even in the baking community, it should be fine to ask what goes into their decision to bake bread, or why they choose to bake bread instead of spending their time baking other things instead. Even if he already made up his mind, it’s fine to be curious about the motivations others.

He didn’t tell you what you can or can’t do, or what you should or shouldn’t do. He didn’t jellyfin is bad or that self hosting in general is bad. He wasn’t rude.

You say it’s an important life lesson to get that it’s ok for other people to have different tastes and priorities, but it’s also healthy to ask people about those tastes and priorities.