Beanie expresses strong skepticism regarding Polymarket's $12 billion valuation, comparing it to OpenSea's overvaluation and predicting a similar decline. He views prediction markets as a "bubble" and a "fad like NFTs," citing Polymarket's lack of competitive sports betting experience and poor in-game liquidity. Investors should be cautious about the high valuation and potential for significant downside in Polymarket and similar prediction market platforms.