Secular Buddhism and Suicide

I have a limited understanding of Buddhism, but let me first explain my perspective. More traditionally, Buddhism is concerned with achieving enlightenment and ending the rebirth process. From a more modern perspective, Buddhism is primarily concerned with ending suffering. I realize that it is much more nuanced than this, but I am speaking in gross generalities. This question really only applies to the working, modern interpretation of Buddhism. If the goal is to end suffering, why don't Buddhists simply kill themselves? I suppose this pertains to how they see themselves after death. If they believe in some shade of "nothingness" after death, I would think all Buddhists would commit suicide. I apologize for this question being so broad. I also understand that different sects of Buddhism will probably have different answers. I am mostly curious as to what modern, practicing Buddhists believe--particularly those that reconcile Buddhism with modern science. This question is really a segue for me to understand the existential beliefs of Buddhism. I can read about the teachings of Buddhism, but I do not understand the "why" behind it all. If I can understand why Buddhists do not commit suicide, I hope to gain a greater understanding into how they view the meaning of life.