Why do so many kids and adults alike feel it's okay to kill insects!?

I currently attend high school, and I see so many kids go out of their way to kill a poor insect! There is a Wonderful student who when in gym class saw a spider that the gym teacher didn't notice. She yelled "Wait a spider!" She leaped across the hallway and got a peice of paper to help move the spider! I was so glad that the teacher said that he wouldn't kill it, He even helped to move the spider out of the way! Then we went to begin class, when this kid who could mean purposely, when no one was looking stepped on it, and squished it! The sick part was that when he was smooshing it into the ground he was smiling and getting a sick pleasure out of it! I was one of the only people that unfortunately saw it! I'm a kind person, but after that I was ENRAGED!! I would love to hear people who understand what I am saying! He has done this more than once and I always seem to be the only one that seems to have the empathy and compassion to where I am drawn to tears, when I see these horrid acts of cruelty!! For those of you who have this empathy and spirituality I LOVE YOU! Please post, so I can hear from You!!