I'd just recommend actually reading the manga lol.
Gaara was hated, isolated and eventually attacked numerous times by his father. The only person who showed him love at a young age was his uncle, not his siblings. His uncle then says he cannot forgive Gaara for killing his sister/gaara's mom (in childbirth) and tries to murder him.
So Gaara now is completely alone, he is told by the one person he loves that he's irredeemable and better off dead and his father continues to send assassins his way.
I don't want to read Naruto ever again, because it's wasting my time.
Gaara was showed later on the panels with Temari and Kankuro who cared about him. Even I remember how we saw his saying: "I was alone on the scan where you can see Temari and Kankuro standing near him.
Again Naruto all about flexing. But character didn't make any sence. If that was only Gaara's problem, I would take it, but this problem happened with almost all Naruto characters:
Let's take another example: Neji
He was fighting against Naruto to prove that he is a slave of his destiny, that he can't get free from the Main Clan line.
But before that he was fighting against Hinata and was saying that she could not defeat him, because he was better than her. But Hinata was a Main Clan line member. How does this all make any sense to you?
Also, please answer me the reason why Obito attacked the Leaf Village in the very beginning of the story? This was the main secret quest to learn the truth behind that event, so why Obito did that?