It was probably just kids who didn't have enough sense to be home where they belong. And, it was just one egg. It doesn't sound like you were "targetted" for vandalism.
One of my daughter's friends TP'd our house and thought it was hilarious. I was furious because of the mess. It was nothing compared to how pissed her mother was though! First of all, she was trusted not to leave the house when mom went to pick the little brother up after going to the movie with Grandma and second of all, she wasted 8 rolls of toilet paper.
Fortunately, with the price of eggs these days, I don't think you'll have to worry about it happening frequently.
I'm sorry it happened, but I really wouldn't overthink it.
It was an egg.
Kids do really stupid things sometimes.
Best wishes.