The weapon industry is very profitable and consequently very powerful. It is probably owned by very powerful people who can change the politics of United States and many other countries. They need to sell weapons to satisfy their greed of making more money. From weapons of mass destruction to weapons for crazies' consumption.

Some people have pointed at mental well being more important than availability of guns but if you think about it, a person with a knife can be easily subdued but not a person with gun and the amount of damage that can be done with a gun is much larger than without it.

Everything boils down to economics. How do people even get violent ideas like that? People have been constantly desensitized by the violence that is seen around them. Commercial for profit companies have been selling violence in the form of movies and brutal video games in order to make violence seem acceptable and common. The respect for life has been sold for the profit of the corporations. Even governments partake in mass violence killing thousands of innocent people and it is considered fine as long as the profits of the corporations that control them are intact. The powerful companiesthat control the media and other profitable industries have no qualms  glamorizing mass killings and violence in the form of fighting, shooting or in acts of war.

What does all that makes us? Sitting ducks doing our own thing and hoping that nothing happens to us.