If it were that simple then these markets would have been shut down already.
Matt Levine has gone into great detail about the legal chicanery that brought us here, but it summarizes as "it's not gambling, it's futures trading".
This seems like nonsense to you and me (and Matt Levine), but our opinions are irrelevant here. The courts' opinions are, and so far they've been coming down on the side of the prediction markets. Mostly.
So by definition - as weird as it is - it's legal. So far.
But we're talking about legislator's opinions here. They make the law. A good way to influence the courts, as a legislator, is to write a law.
Even if you are a state legislator, and federal courts are mixed, you should write the law to raise the issue salience and get the federal law tweak.
Courts really are not the end-all-be-all when we're talking about legislators making laws, that's silly.
> If it were that simple then these markets would have been shut down already.
Sure, just like storing a bunch of classified docs in a Mar-a-Lago bathroom was.
You are mixing up "currently getting away with it" for legal.