Fan edit idea to change the ending (spoilers)
If anyone has say a fanedit (dot) org account, here is an idea someone could do to change the ending to make it look like he kills the last guy in his apartment possibly? Would love to re-watch the film with something like this to change it!
After he walks out have it cut to a close up of the TV in room with a similar image of a stock rating (doesn't have to be same as can be different images changing when he leaves) then edit sound of footsteps in, a gun shot and a body falling to floor with then footsteps exisiting.
Not very realistic yet is best I can come up with to fix the dull ending as for sure he should have shot the guy.
Also have a newspaper article image edit flash on screen when Fassbender is resting with girl with a "Rich millionaire found dead in apartment" headline perhaps.