I like to describe how money is, essentially, a ledger system. Blockchain technology is simply a distributed ledger system which everyone agrees to and can only be added to by those who are in agreement about it. Essentially, blockchain technology is the best form of money ever invented. From there, I talk about the 10,000 BTC pizza. I ask them, "How can 10,000 of something be used to buy a pizza and then later those 10,000 tokens of value are worth $6.65M?" That's not a hypothetical, so it really gets their noodles cooking. Then we might talk about how value exists in the moment of exchange and, currently, there are exchanges where people want STEEM and SBD, just like they want bitcoin (which is currently worth around $665 each). I talk about how the Bitcoin blockchain is creating new value all the time and the market is supporting it. Steem does the same thing, but instead of giving it to everyone who validates the ledger, it gives a large portion of it (at a 9:1 ratio) to the content creators and curators.
I gave this little talk at Liberty on The Rocks tonight, actually, and it went really well. If the site was open for signups, we'd have a few new members already. :)