The tech powering this is called Spark — a Bitcoin L2 that validates transactions at broadcast time. Spark checks for double-spend risk, fee adequacy, and replace-by-fee flags before the transaction...
Why does this matter? Polymarket has processed billions in volume. Every user who deposits via Lightning is now using Bitcoin as actual money — not just a store of value. Lightning isn't "coming soon." It's here. The largest prediction market on earth is running on it today.
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