As far as being a motive, what do you mean? That it would make him successful if he actually did what he rapped about? But then what would that matter if he were behind bars for the rest of his life or possibly put to death. The trade off does not seem equal.
The thing that bothers me about all of this is that now we know he waited for them to go to sleep. Therefore, there was no heat of the moment argument where he just flipped. He waited.. and planned. That is scary.
Sam initially stated that he became "Syko Sam," because he wanted to give back to Horrorcore, presumably to repay it for what it had done for him. What did it give to him? Once could argue the most important thing was a sense of belonging; of family.
At some point, he decided that he wanted the respect and adoration that some of the underground's heavy hitters received. He was no longer satisfied with just being LilDemonDog, the web geek behind the scenes. That's the likely scenario for why he even decided to pick up a mic and try his hand at the artistic side.
He gave it his best a churned out some songs and videos, but let's face it, he brought nothing new to the table. His shtick has been done to death in the underground. His lyrics didn't pack the necessary punch and lacked any real substance. I doubt they shocked many people in that scene and inspired even fewer. He most likely became somewhat of a running joke in the Horrorcore inner circle.
Remember, this is a kid who was picked on all of his young life......
Is there really anything much worse than to think you have been accepted as an equal, to have finally found your place, only to have it all cruelly pulled out from under you?????
Suddenly, he is no longer Syko Sam, rather Richard McCroskey, the fat PASSIVE ginger loser..... all of those old insecurities soon begin to creep back into his fragile psyche, but that new persona, Syko Sam, was also still in there... the two couldn't coexist.
Who knows exactly what transpired? We may never know the full truth. Did Emma decide to scrap Sam once he was no longer one of the cool kids? Was the new guy that she was talking to/texting with a Horrorcore performer with a little more "street cred."
I believe that it is a likelihood that Sam realized he couldn't make it as an artist, so he decided that he was going to become infamous, by doing what the rest of them only talked about.... Even better that 2 of his chosen sacrificial lambs were beloved and respected members of the Horrorcore scene that turned on him. Was he really that cold and calculated some may ask? Look no further than his post crime actions and his demeanor once in custody.
Anyway...
The fact that some of the victims were asleep points towards premeditation. This is not to say that he went to Virginia with evil in his heart and murder on his mind. My guess is that there was another argument in VA, which acted as the final trigger, the final straw that broke Sam's history of passivity. Again, we may never know, but I am liking this scenario more and more when I put myself in his shoes.