This is because I still have not heard one rational reason why anyone needs an automatic weapon ....
Because our government supplies them to enemy countries, cartels, and rebels who would do us harm.
As long as our own government is supplying these same weapons, and far worse, to people in other countries around the world, who at any given moment would do us harm, then we as citizens should have every right to own the same weapons. If it is good enough for our government to give some goat herder in the Afghan mountains, then they have no case not allowing a citizen of this country to own one.
And, I'm sorry but it is in the very nature of Americans to seek to acquire and own that which authoritarian governments wish to ban. I have a whole collection of historically banned books and will probably buy a bump stock (actually tried the other day but Cabelas was out) solely for the fact that our government wants to ban us from owning them.