What ever happened to those mass killing/shooting terrorist events that popped up mid 2010s? They used to happen a lot then just disappeared

Sloppy jobs.

low return on investment. ISIS was systematically exterminated as a result. It’s just more efficient to focus on local gains rather than allocate resources towards international actions which cost significantly more than they achieve.

Plenty of groups in the middle east, such as those in yemen, iran, pakistan, afghanistan, or syria could carry out military action against civilians in the west. They chose not to because it’s counterproductive. The NVA made the same decision in their struggle for independence against the french and americans.