maybe you could get all of your family and friends together and dig a ditch around your house.

The size of firebreak required to stop a wildfire is rather large. Your average family/friends group won't have the necessary equipment to dig a firebreak. A few people with shovels isn't going to stop a wildfire.

The CDF employs gigantic buldozers and other equipment to clear firebreaks, and even those are not always effective depending on the wind conditions.