Friendship is unnecessary

is one of those things that give value to your life. Like philosophy and art.
Laughter is unnecessary to one's survival, but it adds value to it nonetheless.

in life: reproduce, earn a living, give something meaningful to the human race all without friendship. But our lives our enriched by others who go through all the same stuff as us and who stand with us. This type of friendship in a way has no responsibility like a marriage, no emotion baggage, it's just freely enjoyed by each party. We can live without philosophy, art, music etc. but life is enriched by it.