There's a difference between friends mates and acquaintances and there's different kinds of friendship too. Deep question. Not sure I've got the mental capacity to explore more deeply atm. 

My oldest friend I've known for 28 years now. I've got mates I grew up with who I've known considerably longer, but they're not part of my day to day life. But there's maybe three people outside of family who, if something were to happen to them it'd  have a significant impact on my day to day life.