I don't think what the perps ended up with, is necessarily what they went into the crime expecting. In fact, I think whatever "plan" they had did not go as expected. Unless DW went to the house alone, with the sole intention of torturing and killing the S family with the money a nice bonus, I think the "plan" went seriously awry. If they went for money, I think they intended to get much more than $40K. If they went for cars, the Mosler is the most valuable/coveted, but never made it out of the garage, past the Audi blocking it. Between not understanding how difficult it is to raise large sums of cash on short notice, having a disorganized/brutal monster in charge of controlling the household, and people not showing up when/where they're supposed to with everything they're supposed to deliver, very little seemed to turn out the way a mastermind would design his crime.
Seems more like a crime planned by an amateur race-car driver who can't fully differentiate between reality and fantasy, than a career criminal.