To put it simply, your own value, or atleast your opinion of it, is mostly down to you. You can see no point in life, but then there's no reason not to think you're amazing. Yeah you'll be arrogant and annoy some people, but then everyone annoys someone. In fact, most people annoy a lot of people.
I tried to kill myself a few times, and eventually realised that I was just hurting myself just cus I rated myself low. So I played to my strengths, and decided that I actually am pretty amazing, even if I have major major flaws. The flaws are no bigger than anyone else, cus if you watch people long enough, you realise that most people are equally messed up.
But then, I also know that I can't help you. You should seek professional help, but even they only provide guidelines and suggestions. You just have to live, learn and grow. All that's needed is a change in perspective, but that's incredibly hard to do. Like I said, I had to die to figure it out.
Everyone is different, so I dont know how you're gonna figure it out.