Why does everyone in the show hate Hyacinth?

i don't understand it either. i think she's hilarious. i wouldn't want to run away from her, i'd want to talk to her and egg her on to talk about her sister with the swimming pool and room for a pony, and about the latest goings on of Sheidan. in real life, you would just laugh at her, not be terrified of her,

I find her quite hilarious. I love how she tries to move up in society, while trying to ignore her lower station of Daisy, Onslow and Rose.

She is good at heart, but is trying to desperately to improve her station that is she is clueless of how others view her.

I have to side with the OP about this subject.
Sure, Hyacinth can be a pain in the butt and even rude to people some times.
And I can see why most of the other characters don't particularly like her.
But I feel that some people around her tend to exaggerate to a ridiculous degree.
Yeah, I guess that we're supposed to find it hilarious when they act like they're scared of Hyacinth.
I can't see any humor in this at all though, despite how I find this a good sitcom otherwise.

No idea, they often seem just as bad as or even worse than Hyacinth.

I don't know. After all she's just trying to keep everyone up to standard.

It was just part of the comedy of the show.

She was shown as being snobby, insufferable and with very little self-awareness. If people had run up to her shouting; "Hyacinth, it's great to see you", the joke wouldn't have worked.

People who refuse to engage with reality are always a pain in the butt, that's why!

You always want to slap them upside the head and yell "You're not a fucking duchess, you're middle class! At best!!", but it'd never sink in. People who don't want to engage with reality can have incredibly strong defenses against it.

Because the woman is the extreme in terms of being insensitive and overbearing. If she showed the slightest bit of vulnerability people might have had some degree of pity for her.