Here's the core holding in Raich:
Wickard thus establishes that Congress can regulate purely intrastate activity that is not itself commercial, in that it is not produced for sale, if it concludes that failure to regulate that class of activity would undercut the regulation of the interstate market in that commodity.
The similarities between this case and Wickard are striking. Like the farmer in Wickard, respondents are cultivating, for home consumption, a fungible commodity for which there is an established, albeit illegal, interstate market.28 Just as the Agricultural Adjustment Act was designed to control the volume [of wheat] moving in interstate and foreign commerce in order to avoid surpluses . . . and consequently control the market price, id., at 115, a primary purpose of the CSA is to control the supply and demand of controlled substances in both lawful and unlawful drug markets.
Slip op. at 15.