Because nothing is permanent. Whatever it is that makes you want to kill yourself will change. It will get better. It may not be perfect. Sometimes it may even be worse, but its never going to stay the way it is now, these feeling, or emotions. And attitude helps a lot. Give life a chance. It may never be perfect, but it can be worth living. You may meet someone who will help you see that. You may even find out that you, yourself can tolerably be the best friend you have ever had. Give it a chance. I did, and I am glad.