It provides a safety net by pooling the resources of the community to support the less fortunate. This prevents people from having to sacrifice their long term goals because their short term needs may not be otherwise met.
Also in contrast to capitalism that treats society as a zero sum game ("I can't get ahead unless I take something from someone else") socialism is a benefit multiplier ("I'm part of the community. By making the life of everyone in the community better I'm also improving my own life").
The man can't leave if he's shitting his brains out.