People think that suicide is just stupid, or attention seeking.
Have you ever felt so depressed that it feels like nothing in the world matters? Have you ever been so depressed you've honestly believed that you're not real, that this is all just an illusion and the only way to wake is to die? Have you ever hated yourself so much that all you want to do is to destroy yourself completely, once and for all?
If not, then you have no right to judge people who commit suicide. You have no idea what it's like to feel like there is nothing to live for. You might see a million reasons to live, but people who want to commit suicide don't.
People who are happy can't possibly imagine what it's like to feel absolutely emotionless and empty. People who've never been bullied or abused have no idea what it's like to have someone treat you like dirt so much that you start to believe it. People who love themselves and have self confidence and have never hated themselves so much that they're started just abusing themselves in any way they can, but it's still not enough, don't know what it's like to feel that way.
Don't assume you know what something's like just because you've seen how it appears on the outside. Nobody really knows anyone else as well as we think we do, but this doesn't give us the right to say that their suffering is unimportant, and that their struggles don't deserve to be treated as real.
And lastly, saying suicide is stupid is just going to make people who want to go through with it feel worse about themselves, like they're pathetic and weak, which they're not. So in actual fact, being made to feel as though they're not good enough because they're going through a hard time, is one of the things that can cause suicide.