I don't know. I've been single most of my life, now in my 50s. I've not lived with anyone since i left shared houses. I've had some relationships, but they've mostly been LDRs, so in many ways, I was still single.
There have been times in my life where I've wondered what's the point, because I could collapse and fie here, and no one would notice for a while. I'm not even working currently, so there wouldn't be concern because I didn't turn up for that.
There are things which are tiring about it, but there would also be things tiring about living with a partner, just different things. I like being able to do my own thing. I long ago decided that not having someone else with me wasn't going to stop me doing things, be it travelling, going to a restaurant or the theatre or the beach or whatever. I enjoy my hobbies, I enjoy meeting up with friends, even the married ones. I miss sex, but I'm okay with casual sex, and Tinder is there. I do have a sort of partner at the moment, but his job is very busy, so I don't see him often during term time, and in practical ways, I am single.
My parents always did their own things as well as things together, so I always expected grown-ups to have their own Iives and some independence, and I think that helped mum a lot after Dad died; my sister's PiLs only did things as a couple, so he was really lost when his wife died.
I don't think life is pointless if you're single, but I do know it can feel thst way at times. It's prompted me (along with redundancy) to change career to something where I think I'll be making more of a contribution to others. Maybe if I were married with children, I wouldn't have felt the need to do that, but I think all areas of life need to give you some meaning - family, friends, work, pastimes, all of it. It also means if one part isn't currently doing it for you (like being single when you'd rather not be,) then at least not everything else should feel empty too. If you rely on a relationship to give you all your meaning in life, that's rather a burden on the other person - you need to bring something, too.