Avengers: Infinity War - 8 Compelling Theories About The Hulk
4. He Lost What He Loved
The other big story element of Planet Hulk/World War Hulk that might come into play in Thor: Ragnarok and beyond - and which could explain why Hulk is angrier than he was before - is the death of Hulk's wife, which inspires his rage against the Illuminati and his vengeful warpath.
Obviously, there's a slight problem here, in the fact that Hulk has never been married (even though he's had two love interests in the MCU already), but there's no reason to suggest that the same emotional dynamic could be explored. In the run up to Thor: Ragnarok, Hulk could have made personal relationships on Sakaar, and when he loses one, even though the Illuminati couldn't be responsible, there are ways to write in a reason for Hulk believing the Avengers were.
Maybe their actions drew the attentions of the Chitauri to Hulk's position? Perhaps Thanos learned that Hulk was on Sakaar and struck a personal blow at him to try and wipe him out as a threat to his own conquest, and Hulk believed the Avengers' meddling in his desire for the Infinity Stones to be the cause?