Rock bottom is a place where you expect nobody to help you, at all, ever, full stop.
Homelessness in our society is seen as rock bottom. Homeless people are ignored, maligned, and often feared. But once in awhile someone will be kind. Those kindnesses are so important and so well remembered, as they are so few and far between.
Life is hard and a damn mess. It's amazing half of us make it through. Often there are long stretches of darkness that seem impossible to overcome, depression. Getting out or surviving depression can take enormous effort and diet can be a life savior.