How do marijuana users "endanger all of us"? In any way that alcohol users don't also "endanger all of us"?
Once a person is so reckless as to question the wisdom, nay, even the authority of our benevolent government in the matter of marijuana, then that person is more likely to question the wisdom of the government in other spheres.
If we do not have absolute faith in the wisdom of the American people and its various governments, and obey with a glad heart their every regulation, then the sky would fall - right on our heads!