As a skeptical Buddhist, I'm just trying to rack up good karma by helping people and doing kind things so that on the off chance reincarnation exists, I'll have a better shot in my next life.
Although I doubt rebirth is real, I figure it also adds meaning to my life to be kind, develop patience and compassion, etc.
For what it's worth I think people seek to gain a lot pragmatically from Buddhism, as it will inspire us to be kind to others and ourselves and if rebirth doesn't occur, we don't lose much by being kind.
But yeah Buddhism would suggest suicide to be a negative karma (not morally bad, but just recognizing it does cause suffering, which You have to come to terms with if you're going to ctb anyways; people will be sad). It's a pretty mild karma in the grand scheme and there are contextual exceptions (e.g., look up the burning monk in Saigon, 1963). Essentially the negative karma is the sadness to family & community. You won't go to hell or anything though (not without an abysmally large number of lifetimes of negative karma, at least; one act will only set you back proportionally). You'll simply be reborn into a world where the sadness and it's ripple effect goes out into your next life.
As I said, I think it's unlikely, but I'm preparing for the possibility.
If the self is impermanent and can cease to exist, it stands for reason that consciousness is still over the fence; the universe experiencing itself. We just don't "see" it because we are stuck identifying/perceivong as ourselves. When we die we become the process of the universe unfolding, including all the consciousnesses that exist. It is not "we" (as remember, "we" died), but the universe (which "you" are now) will experience consciousness again and again through the natural creation of conscious beings.
So the universe will experience consciousness again.
How you make sense of this is up to you. We tend to codify it through personal symbolism (religion) but the fact is that once we are dead that's all irrelevant. All there is appears to be perception and matter.
There's probably nobody manning the light at the end of the tunnel. But you can take a few steps towards that, and be easy on yourself while you move towards what you'd like to construct as that light. Giving yourself patience and ease in just existing, and should you choose to die, also not hating yourself.
Shame is a much greater negative karma than suicide will ever be. In fact, it probably results in much of it.
I hope this helps.
May you find peace in living or dying
- Rhizo