As someone from a completely different generation, it just stuns me how much information young people share online nowadays. It's scary. I mean, just from what people have shared from the victims' social media posts, we know the names of their boyfriends, their exes, their room mates, the dog, and what their bedrooms look like. We've heard their voices, seen them in videos, know their future plans, who they're friends with. And I'm not even in the same country!
I think social media is the key. Even thought I'm older and know that social media only displays the "highlights", I've found it difficult at times in the past when things aren't going too well and online it looks like everyone's having an amazing time. So God knows what it's like for young people.
I can see the attack being planned purely due to envy and jealousy. These guys looked so happy and loved and full of joy and someone hated that. They saw it on social media and they wanted to destroy it.