I'm good for nothing in the world.
People are usually good at something, perhaps you haven't found what you're good at yet?
I don't think I'm ever going to find it.
Since you feel like you're good for nothing, you should learn skills and try to become skilled at something. If you don't try to improve yourself you'll stay the same.
I'm never going to be the best at something so I'm going to fuck my life and hope it'll get better.
I really think you should put forth the effort into learning something, like a trade if you are unhappy with your standing. Everyone starts at the bottom, even the giants! So if you stick with it and put forth passion, you would have something to contribute to the world.