To this day I still do not understand exactly why "everyone" hated Ben as soon as his secret identity was exposed in Ultimate Alien.
Yes, Harangue slandered his name all over television, but besides his questionable credibility considering the way he conducts himself on television (including literally broadcasting his crimes on his own program)…he's just one guy.
Why would "everyone" side with ONE news anchor/television host? Who was factually wrong and biased in his reports anyway, claiming that Ben is a threat to society while replaying instances of him helping people?
Would normal, sensible people with common sense not realize that saving the world is not something to hate someone for?
Did people not KNOW that right off the bat? Because I'm pretty sure Jimmy mentioned how he did tell people what Ben was using his powers for. That was the whole purpose of exposing his secret identity to begin with - to give him the recognition that is rightfully deserved.
I can understand perhaps being afraid of someone with so much power, but that wasn't even brought up as a reason for this "hate."
Did people hate him for "lying" them? For hiding his powers? That also logically makes no sense because he's allowed to want to have some level of privacy. Especially since being a superhero isn't exactly a safe life choice. So, anyone who knows of it and is involved with him is an immediate target. Hence why his family got targeted as soon as his secret identity was revealed.
Despite all of this affecting Ben to the point of him considering to drop out of high school entirely - to continue protecting the lives of innocents, might I add - he's still shown considering how being widely known could help him be a better superhero.
But, the plotline reinforces how there is still something to dislike him for, reminding us that "everyone hates him" and that he isn't all that impressive, even having his girlfriend be the one to say those things.
Ben: "Maybe it's for the best. Maybe I can do more good as a public superhero than I did in secret. Sure, most people think I'm a menace now."
Julie: "Only 26% of adult viewers think you're a menace...74% think you're threat."
Ben: "My point is once people get to know me, I can win them over."
Julie: "That hasn't been my experience."
I don't know what "experience" Julie's talking about here exactly, as she might be alluding to something that happened off-screen, but if you know anything about Ben as a character, it doesn't make sense to say that a superhero who's done everything he has in the short amount of time that he has wouldn't win people over.
Bottom line, there's no valid reason nor purpose to hating him.