I think, in reality, it's the kind of arrogance that comes from there being no repercussions. It happens all the time near me - nice area, low crime, generally affluent. But, there's a group of little shits who go out stealing things - motorbikes, lawn ornaments, signs from businesses... and, no one does a single thing about it.
Now, the police just don't have the time and resources - I somewhat understand that. But, what gets me is the local Facebook page, whenever some posts saying they found a burnt-out bike on their dog walk or they had to remove Tesco trolleys that had been upturned and strewn on the main road or that a bat house for hibernating bats has been burnt to the ground killing all the bats, banging on about "well, we were all young once" and "didn't you ever have any fun"... Like, yes, I had fun as a teen and I never once set someone else's property on fire, never once put someone's life in danger and never told expensive items from strangers - ever. And, if I had, 99.9% of my parent's generation would've absolutely lost it with me and not one would've thought "nah, kids will be kids, let them commit arson".
I have no doubt that these two numpties have been doing this kind of shit for too long, unchallenged and under the guise of "let them have their fun". But, now they've grown up, struck the wrong target and learnt too late that actions have consequences.