Every Polymarket trade is recorded on-chain, so you can watch the wallets of large traders who have made money over time. When one of these proven wallets opens a position, you copy it (or get in just ahead). The edge is borrowing the research and conviction of sharp money. The danger is being their exit liquidity, so you need rules to avoid buying right as a whale is about to sell out of a position.
Markets on Polymarket where whale wallet tracking is the natural play: