A personal psychological POV:
From the minute most of the guests boarded the boat, the long lasting social masks are dropped one by one.. every word they had in their personal interactive dialogues encouraged in dropping their masks down.. they felt safe once they left their "real" lives behind, this proved my theory by the last dish in the movie and their acceptance of the Chef's end. Yet this was not the case for all guests of course, the oblivious guest, who will carry on and on turning their heads away from the reality till it destroy them due to their idiocy of comprehending the situation around them or to continue ignoring fighting the inner war by pleasing others first, which will end in self destruction, there was only one way- out for this guest. As for the survivor, talking about the right place in the right time, her understanding of people based on her experience, which forces clients to extremely vulnerable and open to her, including the Chef, plus what she has observed from them made her aware and gained more grasp of how to deal with people’s inner demon to survive.