Why don't people just...

Finally watched the entire movie this morning. I liked the film. I really don't understand when people come into money they do such stupid things. If you come into money like they did you never buy a flashy car like that Chevy. You buy something like an Accord, Corolla or Camry (something to blend in)& never leave pictures around the house. Honestly if the lead guy was hell bent on killing his neighbors then why not just kill Slater's character? Cop dead, free money.