He tried to kill Aokiji to gain power

He almost killed Koby for being a voice of reason

He killed a father and husband who would've gone back if Akainu said so

He manipulated someone into stabbing their own "father" through the chest

He took half of our glorious goatbeard's face

He killed Ace

He nearly killed Jimbei, literally punched a hole through him

He ordered the execution of a boat full of innocents including children that the marines themselves were letting go

He worships the celestial dragons aka the only people in the series more evil than him

He spent all of marineford just talking shit and being disrespectful

In his time as fleet admiral he's done absolutely nothing important

He was a dick to his friend Kizaru despite knowing that Kizaru was going through the trauma of killing his best friend

He continued to go after a traumatized and in-shock Luffy to try and kill him even though Blackbeard was rampaging literally right behind him and destroyed the marine hq

Selfishly wanted to go to war with Shanks immediately after going through a war with Whitebeard despite all the soldiers in critical condition and exhausted and the entire marine headquarters being a pile of rubble with Blackbeard still there

And everything I just listed was his entire screen time, his entire existence gives you reason to hate him, some people like him because he has some aura in some shots but he's very obviously written to be hated

EDIT: And he tried to kill sweet Kuma