I usually start with: "Bitcoin is basically a public ledger, one that anyone can write to but somehow everyone trusts. We've never had that before."
The conversation then usually goes in one of two directions: 1) how does Bitcoin achieve this, or 2) why does this matter? I trust that you'll be able to take it from there :)
I like starting with that because it focuses on the actual technological innovation and what's got people so excited. It works better than talking about the gainz since 1) not everyone is interested in gainz and 2) gainz are not guaranteed over any particular period of time and 3) they probably know someone who got burned chasing gainz
FWIW: from my experience people have no idea what is "ledger", especially non-native english speakers... I had no idea what that means before learning about Bitcoin.
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I think this is fine, as long as they can grasp the overall concept of a ledger.
Sometimes people will ask why we haven't had a trusted public ledger before Bitcoin, at which point I will discuss the problem of everyone keeping their own copy and the double spend problem
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