I'm starting to really believe that the killing was the main objective as well, but I have a hard time with the "thrill kill" theory, for several reasons. If you wanted to commit a murder for the thrill of it, would you not go out of your way to avoid witnesses? Why go to the victim's house and leave with him, after being seen by two​ eyewitnesses from as close as 10 feet away, and then continue with the murder? That makes no sense to me either IMO. So what are we missing?
Here is how I see it
--- They scouted out the place , saw it was rural , places to hide the Yukon , minimum witnesses compared to if they met in Hamilton like Tim suggested
--- They had Tim on the phone as they walked up the driveway so they did not have to knock on the door (less witnesses)
--- Tim would have been an excellent witness but they had no concern because they knew he would be eliminated.
--- They would not carry the gun unless they planned to use it . Auto theft is a minor charge compared to carrying a loaded illegal handgun. As a matter of fact the biggest deterrent for criminals not to carry their illegal weapons is the risk of police finding it if they get stopped for a minor infraction.
Personally , I would change "Thrill Kill" to ... "Thrill Of The Plan" .... they fancied themselves smarter than the killers in the movie "Fargo" (wood chipper) .... or Willie Pickton (wood chipper and pigs) .... they convinced themselves they had the best way to eliminate evidence .... the last thing on their mind was getting caught .... they felt infallible within their own fantasy plan.
And lets face it , they would have succeeded if not for the huge publicity (rare) and Igor spotting the ambition Tattoo. That includes the temporary employee at the hangar , without the huge publicity he would not have thought twice about another vehicle in the hangar
Thousands of vehicles are stolen every year in the Toronto area , and plenty of adults "go missing" , it is routine , and it is rare for police to do much more than fill in a report , they simply do not have the resources.
The reward for DM would be the making of the "clever" plan and having it succeed. Outsmart everybody. Prove to himself and his small circle of friends that he could indeed be successful at something.
However , DM's list of successes remains very short.