90% agree, the CFTC doesn't consider these futures contracts, it regulates them under its "contract market" authority, that Congress designated and updated periodically over time
This is the authority on the CFTC's own website on prediction markets "For more information" section
https://www.cftc.gov/LearnandProtect/PredictionMarkets
https://uscode.house.gov/view.xhtml?hl=false&edition=prelim&...
And yes, both the Supremacy clause and the Interstate commerce clause neutralize any 10th amendment claim, unless the Federal government or any of its agencies was completely mum on the activity. But since the Federal government has exerted authority over that industry, via the interstate commerce clause, states can pound sand.
Has any judge every ruled using the 10th amendment in a federal case?
Yes, I know it's not common but it is used https://www.law.cornell.edu/constitution-conan/amendment-10/...
Federal judges and SCOTUS have some times ruled in favor of states or in favor of the federal government with the 10th amendment being at the center of an argument
Oh interesting, I didn't know that about the contract market authority.