Why does America have so many shootings?

Among developed countries, America has by far the most shootings. This could be attributed to the accessibility of guns. The shooter could be seeking revenge of bullying, have a high exposure to violence, or desire fame. Often the killers have severe mental illnesses or are abusing drugs. For future avoidance of the mass shooting issue, more empathy could be shown toward mental illnesses, effective bully prevention programs could be put in place, and changes could be made in gun policy. Unfortunately, America's society is becoming increasingly violent and narcissistic than ever before. Acceptance of immoral behavior in music, t.v shows, and movies is widespread as well. These flaws in the American culture are factors that cause shootings which would demand a substantial amount of revolution over a period of time and a monumental change of the modern American lifestyle before they were corrected.