Why would ’everybody’ try and want to be in one if they bring no joy to anyone
Not everybody does. You're labouring under the misapprehension that people in relationships are happy, and that being in a relationship is the deciding factor. That's not how it works. Generally, if a person is happy single, they'll be happy in a relationship, and if they're unhappy singe, they'll be unhappy in a relationship.
You need to find how to get happy first. You need to be the person who brings fun and interest into your life. You need to be the person who brings the love of things/activities into your life. You need to be the person who brings passion into your life.
Otherwise, if you attracted someone, it'd be someone who was into people who were bored, had no passion, and were generally pissed off with life. Is that what you want your future partner to be into? Because if he is, he's not going to be in great psychological health himself.
You are looking at relationships as 'the thing that everybody wants, in order that they can be happy', but it's really not like that. Get happy first. You can't have genuinely run out of things that you could try. When was the last time you felt excitement, and what was it about?