Well in this type of situation just like you say that it just seems like you are talking to someone who is or haven't hear about internet before and trying to tell him or her how internet works.

I think how you can tell in this scenario is trying to find a suitable easy to understand definition about blockchain to the newbie.

What do I mean by that, trying to make the person understand how it works from the basic as knowing the basic will surely help the novice, what he or she needs to know the prons and cons and most especially how it works.

If the novice tend to understand much more better then you can not move forward explaining to the person the importance and benefits of the blockchain to individual and to the world generally.

To me to an extent, it is quite difficult to find a easy and suitable definition of blockchain to a novice but I believe that will really help trying to let them know the basic as the basic will crave way to understand more about it.