it becomes rational when life is not worth living. I don't think death is the actual way out, but rather a last resort when all other options have proved themselves to be ineffective.
But it never worth living, no?
1) Death is inevitable. So there's no point in waiting. It's like, mm... You are making a painting but you will have to throw it away after it will be ready. So your effort is fruitless. You can do it, you can not do it. It doesn't matter. But it's more rational to no waste your effort and just throw it away as fast as you can.
2) People can't be happy. Human brain just works this way, that no matter what you have you won't be content. It's an illusion that you can get something that you don't have now, and life will be better. Yes you will feel good. For a couple of days maybe, even months in some cases. But then it will be over and you'll need to seek something else cause you are no longer happy. It's neverending cycle.
3) On a contrary - death is breaking this cycle. You can't be unhappy because you don't need anything, because there is no you.
So death is just better. It is rational to end life as fast as possible.
People accused me that my logic has flaws and is just caused by chemical imbalance in my brain, but that's just how I think and I always viewed life. Yes I am still alive despite I think this way, that may sound contradictive, but I am working on it.