Everyone says going to Hogwarts is amazing and you'll have the best time of your life. Harry even said it was his home.
But ...
I know this isn't a Hogwarts problem and it was done specially for the whole series and stuff but despite having Hermione and Ron, Harry was alone.
Think about it ...
In the second book/film when Harry discovered he could speak Parselmouth, Ron is confused why he never mentioned it and Hermione knows it bad but Harry doesn't understand. What I sort of don't like (probably a film choice) is that in Philosophers Stone, on the train, Harry and Ron spent the whole time discussing each others lives like how Ron has many siblings and a lot of expectations to fill and Harry didn't even know about the wizarding world because the Dursley's shut him away from it all, so why didn't Ron understand that Harry has absolutely no idea what's going on. Also when everyone is all studying Harry clearly feels alone because everyone thinks he's the heir of Slytherin and is ignoring/fearing him but even Ron and Hermione don't really say anything to Harry, so Harry ends up leaving alone.
In Goblet of Fire, when Harry is forced into the tournament even though he didn't want to, everyone even Ron thinks he did it for fame and money. Everyone was sporting the 'potter stinks' badges. But near the end when Cedric was killed, everyone was shocked and despite Dumbledore speaking about Voldemort returning, the Daily Prophet twisted it around over the summer to make Harry look bad.
The start of order of the phoenix, everyone now believes that Harry purposely killed Cedric because he wanted to win the trophy, it's likely they still think he entered the tournament on purpose and probably still remember the 'heir of Slytherin' ordeal. Even Seamus yelled at Harry to the point where Ron (now prefect) had to shut him down. But clearly everyone forgot that Harry is traumatized by the ordeal (he was even physically hurt) and traumatised by his past.
Only when Harry creates Dumbledore's Army and Luna with the Quibbler were able to speak the truth, did Harry have a lot of support and are ready to fight the war.
Up until fifth year, Harry really only had Ron and Hermione, Ginny and Neville, Seamus and Dean in the dorm, everyone else was just existing.