"They thought demons and a rival school threatening their reputation was rough. They haven't seen nothing yet." For Lightning Dust, each day is a high stake gamble, where the only prize is her life and another day of blood and gore. It's not easy, and for those like the mane 6 of Canterlot high who value peace and friendship above all else, it's even seen as barbaric and cruel despite the risks Lightning takes upon herself in what she does.
But as Lightning explains, sometimes the right thing isn't easy to do, especially when the taking of lives is a necessary intervention to save the day. And recklessness in the right circumstances, is a virtue.