Question about ending *SPOILERS*

If you recall, there was another door that was right behind the large table in the dinning room area. My guess is that this is the door to the outside, and the 'Watcher' and victims all entered through this one, and the money was simply left before they woke up as the Watcher, or whoever else placed the money there casually strolled out the aforementioned door.

Well, this whole thing was set up when they were unconscious.

All of the people were probably abducted at the same time, placed in their respective houses, and the money was placed in each hallway. Once the watcher leaves, he doesn't need to go back in. It's the only way out.

People started waking up, and when all 9 in a house were awake, the watcher would play the message about only one surviving.

The only problem I have with that ending is that there's no way to determine how long the process of 8 people getting killed will take. If one group has a psychopath that slits their throats in their sleep the first night, they're going to be sitting in that room by themselves for quite some time while the other 4 catch up.

And then what's the reaction of the 2nd person that survives? They don't talk to each other about it? Try and figure something out? There also seemed to be not much in that room, so if it takes a week or two for one group to kill off 8, and the other 4 are done in 2-3 days, what do they do? how do they eat? sleep? Do they just sit there clutching their money bags the whole time until they starve to death?