Yes.  You have more chance of being struck by lightening than killed in a "mass shooting" like Las Vegas.
(1 in 900,000 chance of being struck by lightening, versus 252 people killed by rifles - of all types - in 2015 - divided into 323 million = 1 in 1,292,000).

The reason why it seems to be a part of American life, is because the News Media makes money by publishing every story about them.

Gun Violence is at an all time low, since the 60's, but the News Media loves to caption such "investigative reporting" by the likes of Katy Couric as "a look at the reasons for the increase in gun violence over the last few years".

People cannot think for themselves, or do the math on the statistics.

From a Risk Mitigation POV, you have more chance of being involved in a Vehicular Homicde (DUI resulting in death).