Friendship was, is, and will be one of the most important factors for one's well-being.
That's from the long-running Harvard Study of Adult Development.:
“People who are more connected to family, to friends, and to community, are happier and physically healthier than people who are less well connected.”
While the expectations and responsibilities of friendship were different in ancient Greece (one's literal life could be at risk without friends), the benefits of friendship overall would still be similar over time. I find the wording of that quote from the Harvard study interesting: “People who are more connected to family, to friends, and to community, are happier and physically healthier than people who are less well connected.” In ancient Greece, one could be physically healthier because your friends and family literally had to take care of all your needs if you got sick or injured. Now, we have some social safety net programs and hospitals and other institutions... but MANY things still have to be relied on through the kindness of friends and family: dropping off food if sick or recovering from surgery, a kind ear or should to cry one, etc.
In some ways, the adage "the more things change, the more they stay the same" seems apropos here.