Gun Laws Do Not Prevent Crime

The answer to preventing mass killings is not more gun control; Stephen Paddock would have been able to get those guns regardless of whether or not owning them was illegal. He would have found a way to get those guns. Heroine is illegal, cocaine is illegal - there are all kinds of things that are illegal - it doesn't stop people from getting them.

Criminals Will Break Any Law

If you are a criminal, you are going to break the law, and clearly, if you're willing to murder, you're willing to break the law about gun ownership. Had the police not found him when he did, who knows how many people he would have indiscriminately murdered?  He still had a hundreds of unused bullets that he was intending to fire at the crowd. He didn't even know who he was shooting; he did not care who he hit. So clearly, someone who is willing to commit that kind of murder is willing to break the gun laws.

Another Person With A Gun Could Prevent the Murder

So gun control would not have prevented him from committing this crime.  Maybe if someone with a gun in the hotel had found him earlier they could have shot that guy in the back of the head before he had the chance to shoot as many people as he did.

Beware of Overreaction

What really scares me, though, too, is what kind of backlash we might have, what kind of overreaction for additional security at hotels. Will it be confined to just Las Vegas hotels, or hotels all over the country? I get visions of checking into a hotel being just like the TSA lines at the airports. There is no way to be sure that a hotel can keep guns out of a hotel room.  They don't have cameras inside hotel rooms.  Is it possible that if they had had extra security at check-in Stephen Paddock would not have been able to get his guns up to his room? He might not have, but this was obviously a premeditated act that took days of preparation, and he could have found a way around the safeguards, or devised another way of killing.