Ah yes, get 2/3 of the states to agree to amend the constitution, so simple. I was just thinking how we could solve climate change by banning all cars and making everyone vegetarian, so simple!

Edit: Okay I realize my comment was a bit flippant. It is a pet peeve of mine when solutions are proffered like this that don't take into account the many obvious difficulties in actually making it work (political, social economic etc.) as if nobody has thought of this. Sure, many people would love to ban and confiscate all the guns, but due to politics there is a 0% chance of that happening in the US, so it is not "simple".