the SCP eventually lead its victims to kill themselves but that does not mean they kill themselves voluntarily.
Think about this, what would you do when you get sick?
Well, if you are "sick", then you would prob have less desire to eat, to act, and to do anything, right?
How about you got really sick? your organs are not working properly, you will feel extremely painful and twisted. I guess without the help of other people, you cannot barely work (I personally almost died once, I know that feeling.)
The victim of this memetic SCP feel that way and think that way, it is not that they are really sick, it is just it seems to them they are completely sicks, and the sickness just goes on and on. Eventually, they will be at the stage they can barely move, eat or do anything. At that point, they will kill themselves but not voluntarily, unless they are treated like a seriously ill patient.
The SCP just spread like a "real" disease except it is not real. It cannot be observed by anything beside the human-beings who are under its effect. Since the idea of the SCP is that it is vital, there will be no cure as well. Of course they cannot be "cured" when they are not "sick" from the beginning. Class-A amnesiac wont be able to eradicate this SCP's effect because it s not about memory but a feeling.