You might, but many people don't share that view.
Stupid and/or selfish, diffecult to say.
It's not selfish, when a person comes to the point of thinking of suicide a lot has gone wrong, they see no way out, they live in pain, most of the time they have a smile on their face, just so that others won't bother them.
How does a person come to this point, some people think like that you should just try harder, but you don't get this through failing of something like school, it's when you fail in life, or at leas the feeling of it.
It's in any case not selfish, some people might find their strenght somewhere to never come to this, but some do, quite a lot actually.
As for stupid... it depends, sometimes it is stupid, but then i'm talking about that the person isn't stupid, but because it could of been easily fixed.
People who think very low off themselfs often don't let others help them, if they would then it really would be pretty easy fixed, because they just need someone there for them, it's stupid that someone doesn't have this and does stupid things because of it, but it all has a reason.
People who commit suicide are simply lonely, sometimes they have indeed a lot of friends around them, but they are lonely in their hearts, i know someone like that, but she doesn't want to talk to me anymore because she is afraid of sharing things, and she tryed to push me away for quite sometime, but it didn't worked, so now she just went away... i'm afraid of what she is going to do, she has this already for 4 years, and i don't see anything change in the near future...
