Why is suicide said to be bad?

I would think because of the emotional turmoil it leaves behind for family and friends. That and all the unanswered questions +3

There are many reasons why people are against suicide..religious beliefs are probably the commonest of reasons..to take one's own life is often seen as a *sin*..
I believe it is wrong simply because we have been given the chance to live on a planet and to enjoy the things around us and the time we have here is already very short..

We are a creation of God. Life is a gift from God. Suicide is a careless discarding of the greatest gift God could give you. It is also interferring with God's devine plan by taking yourself out of the scene before God wanted.

Because it is DEATH. Death is scary.
Death of someone else reminds us that
we will die. Death of someone CLOSE
even more so.

People also have feelings and an attachement
to the person and would wish to spend a lot
more time with that person. They may even
order their whole life to fit with the
life of the person. And suddenly all this
is destroyed in one moment and often You
can't know WHY. It's painful to see
a person that didn't seem to be suffering
so much (or maybe even seemed happy) decide
that He suffers so much He wants to reach
for the final solution.

It might also give pain to people who thought
they were being trusted and a support to the
person, because the person didn't turn to
them for help, but instead decided to hide
His pain and fears and abandon them, often
without any explanation. The person might
ask Him/Herself questions until the end
of His/Her times: "What did I do? What was
I missing? How did I miss this?" maybe
even "Is it because of me? Did I kill
Him/Her by the way I treated Him/Her?".

This might cause incredible suffering
and trauma to many people that were
left. Some might be afraid to connect
to anyone for many many years or even
ever again, because they may fear it
might happen again.

It is also a matter of empathy when people
are trying to imagine what pain did You
have to suffer to go this far.

This and maybe other things.
This is what the person leaves behind.

Because people have feelings and their feelings are deeply hurt when they see someone they love die. Even though I believe that everybody has the right to end their lives in whichever way they desire (assuming that they leave behind no debt or major responsabilities), I don't deny the fact that it is deeply hurtful. It affects and destroy the lives of close ones.
It is because of that suicide is frowned upon and condemned...

People call it bad because it scares them.

Death is never pleasant no matter what the means

Life is sacred and doing away with one's life is a form of dehumanization.

It is sick sad and scary that you don't know.