Fair point that PASPA was the exception, not the rule, and that the anti-commandeering / "states rights" argument isn't some novel theory. It does happen to be deployed often in cases where businesses don't want to be regulated.

I overstated the court-packing angle, Murphy was 7-2, not a partisan split.

But my actual point is narrower than the constitutional question: in practice, sports betting was confined to Nevada and reservations for decades. Once that dam broke, the path from legal sports betting to VC-funded "that but for everything" prediction markets to the current situation happened really fast, and there's no regulatory apparatus keeping up with it. Whether the dam should have broken is a separate question from whether anyone's minding the flood.