If just explaining bitcoin like fiat money proves it to be unremarkable then they won't be interested in bitcoin, there's no easy way to explain bitcoin to people. Bitcoin is essentially virtual with no physical form and you only briefly explain it, which makes it all the more suspicious. The best way is to give them basic material about bitcoin and ask them to spend time learning about bitcoin. Only then will they see the awesomeness of bitcoin and will decide to participate or not?
I think it would be possible to teach people by comparing it to fiat, if only you could put the differences in there. Assume like this "USA has dollars, UK has pounds, Europe has euro, china has yuan and bitcoin is the digital version of it" that's what I enjoyed when I first saw it.
We all got together as people, and people created their own currency, it wasn't satoshi or whatever that made it what it is, they just founded it, but we took over after him and we made it into what it is today, and because of this, it is peoples money and not governments money. It is digital, it's online, and it's ours, not governments and it's decentralized, so nobody has any control over it at all.
It's a good idea to compare bitcoin to fiat and tell them the difference between the two. But I think we will never be able to explain in a concise way to help someone fully understand the full range of features of bitcoin. Instead, provide them with relevant documents or videos so they can study bitcoin on their own, and we'll just explain to them what they still don't understand. This will save both of them time and give them a thorough understanding of bitcoin.
I learned about bitcoin through a friend, but through his explanation, I didn't understand anything about bitcoin, and I searched for videos and knowledge on the internet to fully understand bitcoin. I find that understanding technology through words is extremely difficult.