I hate to ask, but is that a legit news site?
Daily Star is an awful source but that photo is legitimate. Obviously the note could say anything though, not necessarily a motive (although it seems likely.)
As a criminology student, trust me there
will be some sort of motive. Random violence or "wanting the highest score" doesn't genuinely exist, there is always a genuine motive. Sometimes even the perpetrator doesn't realise it.
I've seen a lot of people suggest he had a tumour, or found out he was dying. That's not a bad guess but having a tumour would suggest that he "snapped" - like Charles Whitman - but it's not like this guy grabbed a gun and climbed a bell tower. This was a well planned, pre-meditated act. Some have also suggested that he was, or was about to be, losing his fortune. Again, not a bad guess but surely the internet would have unearthed some evidence of this? And with spending what he did on his guns, his hotel rooms, wiring money to his girlfriend... it just doesn't add up.
What intrigues me the most, from an investigatory p.o.v, is that he filmed himself, presumably carrying out the attack. We know he had a camera outside the door, at the door and one aimed at his position in front of one of the windows. It's that camera that intrigues me. The first two were obviously "Look-outs" so he could kill himself before SWAT got him, but why film himself? It has been done before so killers can revel in their work, but if he knew he was going to kill himself?
Maybe he watched the footage back between him stopping shooting and the cops verging on him, but that's a bit of a stretch. The whole process of him recording himself feels like a bit of a message. But hey, this is all completely speculative and I can't remember any case where we've known so little at this point. I think we can all agree he was one ****ed up dude and he got off lightly with suicide.
You'd think something this brazen, someone would leave a note. 
