I think it might have something to do with the fact that Kalshi is aggressively running ads targeting young men to get them into sports gambling, and Polymarket isn't. (I've never seen them, but my less-technical brother claims he sees them all the time on tiktok and they're particularly sleazy).

Also, more to the point, Polymarket actually does have at least three active lawsuits against it.

edit: looks like this has something to do with it:

> Kalshi has been a CFTC-regulated exchange since 2020. Polymarket exited the US in 2022 after settling charges with the CFTC, and only came back after buying QCEX, a CFTC-licensed exchange, in late 2025.