Your hilarity is my Grief

Today I personally experienced griefing in SL. My friends have their club on my parcel and it's for live music. They've told me about griefers coming and being disruptive and today while there was a show going on, they came in drove and crashed the sim. These are not fans.
After the sim crashed, we came back and the show continued.
I just don't get how people think it's funny when they cause angst to their victims.
These musicians do not get a lot of money performing. Music and art is in their blood. They perform to the public because they love what they are doing and they give us joy in return.
Everybody wants to be happy. Everybody deserves to be happy.
But not at the expense of other people's happiness.