First of all it is important to note, or actually to clarify and emphasize, that anti-natalism is a moral opposition to the creation of a new life. Anti-natalism should not lead to a moral objection to the continuation of life that already exists. Those who already exist should certainly be aware and act in order to harm as little as possible, but there is no logical deduction required by anyone who adopts anti-natalism to kill themselves, but only not to create new life.
Another important clarification, we oppose reproduction for many reasons, not necessarily because life is necessarily bad for everyone.
But even if it really was one of our main reasons, killing ourselves would not in any way change the fact that life is bad. In fact it would be very selfish of us since it would only benefit us but leave all the other bad things in the world as they are. This might solve our private problem, but leave all the other problems as they are. Therefore for us it is the opposite! It is rather important that caring people stick around and try to make the world better. How will the world improve if those who think it is bad choose to leave it instead of trying to improve at least some of its problems?
Beyond that, suicide is not such a simple option. It’s a decision that usually impacts many people and so no one can take it, or offer it, that easily. We definitely think that it should be each person’s decision if they want to end their life, but we really don’t take it lightly. And it’s not because life isn’t bad, but precisely because one of the factors that make it bad is that there is no possibility of ending it in a way that is convenient, simple, available, and free of harm to others. Life doesn’t come with an off switch. Someone has to kill oneself in order to end her/his life and this is not a simple matter for creatures that are biologically built to survive and have a natural and built-in fear of death. And of course it’s not just a technical matter, it’s also very difficult from a social point of view since suicide is seen as obscene, cowardly, defeatist and ungrateful. And perhaps most of all, it’s very difficult emotionally because people don’t want to hurt the ones who care about them. That’s why suicide is a complicated matter and not a “solution” that can be pulled out easily. Not even mainly for the sake of trolling.
By the way, death and fear of death are in themselves very good reasons not to create people because they are inevitable. All human beings are aware of the fact that they will die at some point and that people close to them will also die. They have to deal both with this fear of dying and the fear that their loved ones will die, and also with the fact that indeed their loves ones will die, that is, with the immense pain of loss.
On the other hand, those who are not born will never experience the loss of loved ones. There will be those who may argue that it is indeed true, but that person who will never be created will not experience loved ones either, and this is also true, but the person who was never created will never feel the need for it or be hurt by not experiencing relationships with loved ones because s/he never existed and therefore never longed for anything including relationships with loved ones.
Returning to the suicide option, it is immoral to force people into a situation from which the only option to get out of is contrary to their most basic biological tendencies, an option that frightens them, an option that is illegal, could be horrific if it does not end in death, and will hurt loved ones if it does end in death. A lot of people are stuck in this impossible and unbearable situation where they suffer with their lives but cannot bring themselves to end them. The fact that the option to end their suffering is so terrible makes life even worse. It is very unfair to force people to kill themselves if they are suffering from the life that was imposed on them. This is not a solution, but to sacrifice them twice.