beyond unrealistic
So the neighbors went outside to kill off the attackers and then murder the family because they were jealous if their wealth?
First of all wealthy people value their lives way too much to even go outside and get in gun/knife battles with other people.
Secondly a night of lawless killing would not turn upper class suburban people into merciless killers. Yes they didnt like them but no normal people would murder a wife and her children because of that, even if they could get away with it.