Feeling hopeless has a lot to do with feeling there's nothing out there for you. It's a feeling of despair, feeling your dreams are crushed and you have nobody to turn to. This often causes whoever's feeling it to overreact to many things, and soon everything comes off almost negativly, and in a rough time it leaves the person with a feeling of uselessness- that there is nothing to live for. This usually happens in unsupportive or uncaring enviorments, and family tends to play a large part in it. It also happens most in adolescence, but for some reason or another almost everyone goes through it at some point. This is partially because humans downplay the emotions of others- it's a common tendancy to feel others are less human than you in some way, simply because of their differences. This is not a conscious belief or emotional state, it's simply due to the basic ego and superiority complex of the average human. Of course, as they begin to spiral downward the human mind looks for someone to blame- and they become aggressive and short tempered, taking things out on anyone. This is soon realized by them, and as a result they begin hating themselves, so their ego spirals downwards and they develop an inferiority complex, believing others are better and have it better as a reuslt- and so the subject still believes others could not possibly understand.
They see others laughing and having fun (although a great deal of the people they see are most likely depressed as well) and as a result think there's something abnormal about themselves- hiding behind a false happy persona to make up for it. They no longer think they're worthy of attention, so they try to blend in and give up their individuality. They soon confine themselves into a cage of their own contradicting views- by trying to fit in and avoid pain they cause themselves more pain and hate themselves for it, but feel they have to continue. At this point they've become so irrational they can't see the flaws in their own reasoning, and when these flaws are discovered they believe themselves to be stupid for it.
This quickly leads to hopelesness, the victim having lost a sense of self and the dream of a brighter future, and seeing nothing to look forward to but pain they could easily become emotionally unstable or suicidal.
Those with high will power can force themselves to overcome it and look on the brighter side, and throw away the past. This is something I did when I was near suicidal, and this is also what Blizzard did. However, those with weaker wills simply cannot do it. I have a friend who is now spiraling and she's simply too weak to stand up for herself at this point. Those weaker people need someone stronger to cling to and help them up, and unfortunately that's not provided in our society- where depressed people are laughed at and falsely stereotyped.
A common misconception is that being passive with these kind of people will help and aggressiveness will hurt however that's far from true. It usually takes a large slap to the face for the depressed person to realize something is wrong- something most people aren't willing to do.