There for some reason are always people who will be miserable, and complain about everything. I don't understand what the point of complaining about everything is, because after awhile people will just tune you our, and then where does your complaining get you? I know that life can be tough, and for some it can seem unfair. However, I don't think you get anywhere by constantly complaining.
Why then, do some people insist on complaining non-stop? I think that for some, complaining is a way to get attention to themselves constantly, and to have the focus to be on them. It is not human to look at someone who is suffering, and then not try to help them out. Unfortunately, there are some people who can't see when they are being played, and that is why some complain, because there are those out there who won't tell some people to stop whining.
Another reason why people complain is that in some weird way, it actually makes theme happier overall. I'm not sure why this happens, but some people are never happy unless they are miserable. Maybe they think that if they bring every one else down, they will be at a more manageable level. This never works, and ultimately the person who always whines just ends up alone, and more miserable than they were before.
I think that as a culture, we have learned to accept that complaining is OK. Whenever you see a reality TV show, there is someone always crying, and it seems that the more drama that is created, the better. When people watch this, especially young people, there is a sense that somehow this is a good way to get ahead in life, and then they will emulate it.
Again, as they say, the squeaky wheel always gets the grease. The quiet ones never seem to get as far as the ones who complain about stuff, or at least make a lot of noise that things are wrong. I can't blame people for trying either, as I know there have been times when I have just let someone have their way instead of listening to them whine. Maybe it is just a good tactic to use sometimes to get ahead, although it is really annoying if they keep doing it for too long.
Ultimately, there are plenty of reasons for why people complain about everything. Maybe they just have a tough life, or maybe they were never taught how to just suck it up and deal every so often. Whatever the reason, there will always be those who aren't happy unless they are whining, and that is too bad. Life is far too grand to just spend it dwelling on the negatives.