When you're in your teens your friends, the amount of them and the calibre of them were seemingly the most important thing in the world. If you had few friends you were a loser, if you had loads of friends you were popular and if you were part of the 'cool' ones then all the better.
And then you leave school and go to university and graduate and start working life and those friends you had probably aren't your friends anymore and the rest of the world certainly doesn't know you were part of the popular crowd. Very quickly you're taught that actually it's the quality of friends you have that matters most over the quantity and having lots of friends isn't the be all and end all anymore.
But your friendships in your twenties are just as important as those in your formative years - they're just important in a different way.