Well, how else was he sposed to mark his territory, **** on it?Not on the range.
Guy sees hooligans engaged in hooligan activity down the street.
Hooligans complete hooligan activity and run through guy's yard as they escape.
Guy fires a couple rounds into the dirt after they run off.
Why? He's not sure. To make sure they didn't come back. Or turn around and charge him. Or...finally, because he's never been in that situation and didn't know what to do. So he did something without planning, and without rational thought.
Basically he reverted to monkey brain (lizard/monkey/human brain analogy) and made noise to defend his territory. He had no fear for his life, or even his property. His territory had been invaded and making loud noises at the intruders after they fled made him feel better.