So MAD

You know what makes me so MAD? I'll tell you.
We have been having some work done in our backyard, specifically a basketball court. Luckily we know someone who used to be in our ward that does awesome concrete work. He did our side driveway last year and now he's had a free week so he could do this court for us. He was supposed to pour the concrete last Thur and Fri but the weather didn't cooperate so he postponed to Mon and Tues of this week. (It's been very stressful watching the weather and having them say chance of rain, the worst thing for pouring concrete). Well, the weather ended up cooperating and they poured half the court on Monday. It's amazing to watch these guys work. It's like a work of art getting that concrete smooth and level. Our yard backs onto a park area and I've been worried about kids getting in the yard with the wet cement pad out there. We put the yellow caution tape up across the fence opening and hoped that would deter most people.
Well, yesterday we had an incident. They poured concrete in the morning and were pretty finished with the job by about 2:30. I was heading out there to kind of guard the area while kids were walking home from school. I got out there too late. Some kids had a thrown a long handled piece of reber on the just finished side. There was a big scrape where it landed and some divots. I was so mad. All that beautiful work defaced by some stupid kids. What are they thinking? They are lucky I didn't see them or they would be in jail today (or worse). I was so MAD!!
Thank goodness I saw it right after it happened and was able to call our friend and he came right back and fixed it. Any later and he wouldn't have been able to fix it.
Why do kids do stupid things like that?