Distressing how many self-proclaimed "conservatives" refuse to get this.
If life were as simple as you seem to think it is, no one would ever disagree about anything.
So where in the Constitution is the authority to police within-state marijuana matters?
As I said, there are those who believe the Constitution IS a suicide pact. It appears you are one.
There are many things the government does that aren't constitutionally right. When you can say I won't have to bear the wash from legalizing destructive behavior, you have my support. Until then, it's not just "No," but "HELL NO!!!"