If I had to guess, I'd say you were an average 17 year old male who has a sense of self-awareness = )
I would have to agree with lonewolf. If this is bothering you have you considered going to talk this through with someone? Learning about why you are thinking the way you do, can really shed a lot of light on the subject.
I read that a really high percentage of teenagers (mostly males) from mid teens to late teens, develop various emotional issues and depression type symptoms. It's evidently normal and natural and surprisingly common. But it can be bad sometimes because people don't realise that it's pretty normal so they people end up thinking something wrong and they dwell on the weird thoughts and stuff, when really you should just try to put it out of your mind, focus on something nice, and get on with enjoying life. And soon enough it goes and you will have forgotten about it. Even reading a book or watching TV or going for a walk or something is great, because you find that your mind just completely goes onto something else.
Also, exercise is evidently like a miracle because not only does it give you something to focus on (for that moment anyway), but it actually makes people emotionally tired as well as physically tired. So if you can do some sport or some exercise each day, it will make you much more likely to have a good sleep without thinking too much.
It is difficult to offer any "ideas," when you evidently dont' want a diagnosis:
"I'm not asking for a diagnosis or anything, but if anyone has any ideas as to what could be going on, it would be great."
In point of fact, if anyone here were qualified to offer a diagnosis (which we are manifestly NOT qualified to do) or were just lucky enough to stumble across a correct estimation of whatever the problem is, that probably would answer the "what could be wrong" problem. But you're not asking for a diagnosis -you just want to know what the problem is.
And that, my friend, is rather consistent with your self-description; now one minute an egotistical jerk, then the next day depressed; now one minute a humanitarian, then, oops! you hate the world. Tell me what the problem is -but don't tell me.
I can see that we, as adults, have once again successfully transformed a promising, well-adjusted adolescent into a sniveling, insecure, self-centered, resentful and bitter young adult -just like the rest of us. Welcome to the club. Sounds like you're ready for a responsible career, family, and two cars in the garage to me.
Actually, I said that just to see if you're still paying attention, and if so, then don't.
Truth is, lonewolf, known to some as "wolfie," probably has it right. I hate it when she's always right but at least it saves me the touble of having to actually figure things out on my own.
But let's get down to cases, here: Start paying attention again. You will note, with your keen eye for contrasting personality attributes, that the outlooks on life you describe are the opposite of one another. Humanitarian -and hate. Arrogant - depressed. Want ideas on what's wrong, don't want diagnosis. This business of opposites being found TOGETHER is a big deal in many departments of existence; psychology, art, literature and religion being examples which float to the top of the pond scum of my mind. And since the ancients noticed this dichotomy and pondered over it, it has taken its place as being a part of the human condition. And in fact, as Socrates and Aristotle and the psychiatric case who thought up that idiotic yin-yang whirly-gig thing noticed, it is kind of impossible to have one thing, without the other. We can't know, really, what "good" is unless we have a notion of what "bad" is. Black, white; cold, hot; you get the idea. And this has all come down to us today in handy little cliches, such as the forehead slap and expression "WTF?!"
And the important thing to understand is that none of these so-called opposites or contrasts exist independently in the world, the universe, or nature. They are all, every last one of them, fig newtons of our 'maginations -we made it all up! The important part -EVERYONE has made up the same stuff. And so, the dichotomy, the contrast, the difference, the oppositions, quite obviously come from within us. And that is how we are, as human beings. In other words, being this way is normal, I regret to inform you. For more on this, audit a course in "epistemology," an ephemeral, obscure and maddeningly subtle branch of philosophy which has fascinated thinking people everywhere and been the ruin of many who are in school on athletic scholarships.
Normal as the contrasts are, what may be getting under your skin, or your gray matter, is their high visibility and rapid change in your own self-concept and self-awareness. That's the part where you wake up wondering who you are going to be TODAY. That might be a bit abnormal for an old and depleted curmudgeon like me, but is entirely normal -and highly desirable- for those in the larval stages of coming to grips with the passage from the chaotic existence of youth to the next stages in actually running the place. Your brain, sir, is at work, defining values, priorities and preferences -defining, in fact, YOU. It would be well for you, I believe, to pay attention to this process and give it a preference above the color of your cell phone. I'm saying to be attentive and to think, look and learn -but don't become so preoccupied as to miss out on all the joys of adolescence.
I'll admit I've been prodding, poking and teasing you here because I detect you are possessed of an intellect that will tolerate if not thrive on it. I say this because it is stunningly obvious that you are a skilled writer. And the only way you can be a skilled writer is by being a skilled and agile thinker. After all, when we think, we think in our own language; if we are deficient in our language skills, our thinking skills are likewise handicapped.
Glad you checked in.