Kids are cruel too. Back in grade school, my classmate had epilepsy and the same thing happened, no one showed up. Back then, I had the pox so I had a really good excuse and felt bad for the dude as he was extremely smart. Socially, he was just shunned.
I have come to the opinion that parents are much more cruel and interested in the popularity contest. Brutal honest fact is most kids are better and nicer than adults. It takes years for parents to reinforce the negative behavior. Some kids are mean and nasty little beasts. Even with good parents.