There's substantial evidence that it makes people live happier, longer and healthier lives, eg [0].
[0] https://mcpress.mayoclinic.org/healthy-aging/a-surprising-ke...
The first thing we look for when his mental health starts to go is social interaction. As soon as he starts to get antisocial we know his mental health is tanking.
Humans need social interaction. Happiness is a muscle and it's best strengthened with other people. Seeing people at all improves mental health.
Humans are social creatures whether people want to believe it or not.
Being isolated and alone will make almost anyone unhappy and unwell, whether that person will admit it or not.
Women, who tend to maintain more social connections, will often thrive without a partner in their old age. Men will often just kind of wither away.
It's a miserable life though; for one, not everyone even has a romantic partner, and even for those who do, being 100% dependent on one person is incredibly toxic.
So yea, while being friendless might not kill you, realistically, adults need friends.
> In my life and in the life of people that I observe regularly, there is no real need for friends.
My condolences. I hope one day you find people that you can actually connect with and care about each other.
I think we just become so comfortable and okay with not being happy that we can't identify we're not happy. Everything becomes a routine, everything is automatic. We maintain systems that ultimately don't benefit us because we're terrified of what would happen otherwise.
Which means you can't let non family members too close.
Most "competition" in our modern world is artificial. Try figuring out who benefits from it and where this mentality originates. You'll find that those two tend to overlap :)
I mean, in the strictest sense no, in that you're unlikely to die if you don't have any. But most people would consider having friends fairly essential to a happy life.