Meh, he didn't actually raise his wand.
http://t2.gstatic.com/images?q=tbn:ANd9GcTPzJ2yM096cWPOOwkwbJFXRzHHDoEFX0zUSIJ_DYaLvelPoQhV
In my mind, there was never a chance that Snape would turn out to be a bad guy, because the underlying theme of the books appeared to be redemption.
On the one hand, you can say that Snape tormented Harry. In my view, it was more like frustration at the entitlement Harry got so wrapped up in. I NEVER liked Harry, weirdly enough.
That kid was totally convinced that it HAD to be him doing everything, all the time. He put other people at risk, seemingly without worry or care.
Oh yeah; real entitlement complex there, what with the outright abuse coming from his aunt, uncle, and cousin... and the confusion that had to come from finding out people put you up on a pedestal for something you don't even remember doing, compiled with people either treating you like the embodiment of a god come to earth or like a pustule. Plus, as to him being convinced it had to be him doing everything; considering that Dumbledore tended to gently manipulate him into doing the things he did at a young age, I think Harry can be forgiven for getting into the mindset that it had to be him; especially after hearing the prophecy. The whole "either must die at the hands of the other" kind of tends to make one think, "great, that means it'll come down to what I end up doing, and if I screw it up, millions of people are going to pay for it." I for one am amazed that Harry came out of the whole series even slightly sane; that's not exactly something that's easy to bear as an adult, being responsible for the well-being of literally millions of people, much less as a kid.
A good 'for instance': We know that patronuses are good for multiple things. They are protecting forces, but they are also communication devices. Did Harry ever, in the entire series, even learn how to make his patronus talk? Or was he so focused on playing the hero that he didn't think that was a necessary skill to learn?
I think that can be explained by what Rowling herself stated in the third book; namely that a patronus is an extremely hard bit of magic to learn as a fully trained witch or wizard, much less a student; the mere fact that Harry was able to pull it off at all at the age of 13 was commented on more than once as being highly unusual. Add to that, we don't find out that patroni are useful as communication devices until the fifth or sixth book; Lupin never mentions it, as I recall, in the third book, when he's actually teaching the charm to Harry, so I think Harry can be forgiven for not seeking out a portion of the charm he's not even aware exists. And after he does find out about it, he's in the middle of searching for Horcruxes and doesn't have the time to learn it at that point. For all we know it involved a more complex incantation and wand movement than just "Expecto Patronum" and no one Harry was around at the time knew the words. Harry wasn't around Lupin much, for instance, in the last two books, the person who originally taught him the charm, and while we know Snape knows how to do it, I somehow doubt he'd want to spend that much time teaching a child he ostensibly loathed (based off of how he was portrayed until the seventh book) how to better use the charm. Now granted, he had Hermione, who was an absolutely brilliant researcher, but as the vast majority of her knowledge was being put to use researching the Horcruxes, I'm not in the least surprised that he ended up putting things he didn't see as being quite as important on the backburner.
Imagine how many times he could've obtained help from a more skilled wizard had he simply utilized that ability.
And that's a later book thing, too. But from the start, Harry was like that. For instance, when he decided to hop on a broom during his first flying lesson against orders from his instructor and go zooming after Malfoy. While we may hate Malfoy, Harry put both of them in danger. It'd probably be an incredibly boring series of books if Harry didn't act like that, but really, he was kind of an arrogant little kid. He was, indeed, very much like Malfoy - just loved instead of loathed.
Me, I see Harry as having merely an overinflated sense of "right vs. wrong" rather than arrogance. Malfoy was arrogant; Harry, on the other hand, had up until that point been downtrodden and abused pretty much his whole life, so seeing someone else be mistreated could have sparked a sense of protectiveness in him toward someone he saw as a kindred spirit of sorts. Plus, Malfoy already rubbed Harry the wrong way; we saw that from the moment the two of them met in Madame Malkin's in the first book, and he's an eleven year old kid; forethought is not exactly going to be his strong suit at that point, so his reaction is to go with his gut. Lots of kids suffer from that affliction until they mature a bit and realize that the first reaction is not always the best one. Plus, it wasn't Harry who put them in danger; Malfoy was the one who jumped on his broom first, Harry just impulsively followed him. The danger came when Malfoy (not Harry) flew too close to the Whomping Willow and nearly got hit, prompting him to toss the Remembrall, IIRC (there's at least a slight chance I'm conflating canon with fanfiction, as I read quite a lot of the latter).
In later books I will definitely agree that Harry should have sought out help on numerous occasions; but as I said earlier, what with the abuse he suffered while growing up and what I see as Dumbledore's subtle manipulations to get Harry to do things (why else would Dumbledore, the man responsible for Harry's safety while he's at school, rarely, if ever, punish him for the numerous times he goes out of bounds to accomplish something Dumbledore ostensibly wanted done?), the likelihood of him ever seeking help from an adult becomes about nil. I'm still astonished he ended up even slightly sane, what with all the mental and physical torment he was put through.
