So where do you find it in the Constitution for the feds to regulate intrastate marijuana policies?
The drug trade is international, and the fraction of it that is not international, is for the most part interstate.
Even granting arguendo that you are correct and that the federal drug laws are unconstitutional, you still bear the burden of showing why an objectively bad thing should be cossetted and coddled by a society that doesn't want its kids turned into choom monsters by self-interested suppliers.