One of the greatest mistakes Marvel Comics heroes have ever made was sending Hulk off to space to prevent him from causing more damage on Earth, where he would come back with a vengeance following the events of World War Hulk. However, the Illuminati and Avengers responsible should be thankful that their actions didn't create the darkest version of the Hulk who would destroy the Marvel Universe in revenge.
The Illuminati, Marvel's secret society of heroes who operated outside the Avengers, made their biggest mistake trying to contain the Hulk's out-of-control rage by sending him into space. Ultimately, the Hulk's shuttle would get sucked into a wormhole. The hero would end up on Sakaar, forced to battle in a gladiator arena before later leading a revolution and being named king. After a self-destruct protocol on the ship the Illuminati sent him in activated and destroyed his new life, Hulk returned with a vengeance. However, Marvel Comics once imagined what if the Hulk didn't end up on Sakaar but was picked up by the warriors of Annihilus.
In Exiles: Days of Then and Now #1 by Marvel Comics, a version of the Hulk who went down a much darker path after the Illuminati sent him to space is revealed. In the reality, Hulk was picked up by the Annihilus' forces, but when he was given a chance to him on the Annihilation Wave, the Jade Giant killed him. The evil Hulk took control of the Annihilation Wave and used it as a weapon to get revenge against Earth, where the Avengers and the rest of Earth's Mightiest Heroes were decimated by their former friend.
The comic shows that if the Illuminati had sent Hulk on a slightly different trajectory instead of ending up on Sakaar, it could have spelled the decimation of Earth. Of course, the same thing could have hypothetically happened in the MCU, as Marvel's greatest heroes should be thanking their lucky stars that Bruce Banner's self-imposed exile led him to Sakaar and not directly into the path of Annihilus. Although, he didn't hold anger against his fellow heroes in live-action, so he might have tried to take down the villain.
The alternate reality story shows the worst-case scenario for the Hulk's exile, as his evil form gets revenge on the Marvel Universe in one of the most brutal ways imaginable. Thankfully, the evil Hulk never came to be in the MCU like he did in the pages of Marvel Comics, as the Avengers weren't responsible for sending the hero to space. Still, it shows the death and destruction that could have happened if Hulk ever got his ultimate revenge.
