Polymarket is headquartered in NYC; it's a US company; it has many US customers, and it knows that, even if it did a wink-wink dance "disallowing" that prior to 2024. Since then, it has explicitly expanded into the US market[1]. It is unambiguously subject to US regulations (if we had a regulator who chose to enforce those regulations).

[1]: "Following the end of the investigations, Polymarket announced the acquisition of QCEX, a CFTC-licensed derivatives exchange and clearinghouse, for $112 million. The acquisition allowed Polymarket to legally operate within the United States under regulatory compliance. The company received an Amended Order of Designation from the CFTC in November 2025 and began actively expanding in the United States market."

https://www.axios.com/2025/07/21/prediction-market-polymarke...

https://www.prnewswire.com/news-releases/polymarket-receives...