The unimaginable tragedy of sustaining yourself off of hate
Because Maul couldn't hate Sidious. You understand that, right? His master had always controlled him, would have killed him immediately if he thought Maul posed a danger to him.
Maul only allows himself to hate Sidious in Episode 8, of 10, of his solo series, 'Maul-Shadow Lord', after he is explicitly told that Sideous wants him dead.
And sure, he wasn't actually trying to surrender to the Inquisitors, that was always a trap so he could pull the cave down on their heads, but Sideous left him alive last time. Sideous left Maul enough space to scratch out a criminal empire, and the next time he reaches out, it's two Inquisitors who are so desperate to find Maul, the thing they ask Devon when they catch her is where he is.
And Maul's not stupid. The only reason he stays on Janix is because he's been directed by the force that he could find one here. He does, even causes her to fall, but Maul has to monologe to himself in the dark, hallucinating, with his legs broken, before he can allow himself to think of destroying the master who has never, never cared for him.
The thing most people don't seem to understand is that Maul values a warrior's death. Him denying it to Kenobi in "Twin Suns" is about the sharpest rebuke he has in him. He can be very eager about dispensing them to all of his opponents. He leaves Gar Saxon and all his warriors to a warrior's death, and if the expected reinforcements-if they get captured instead of killed-that's up to them. The only think Maul will consistently offer to those around him is a warrior's death. And Kenobi did not give him one the first time.
You see, the proper thing to have done would be to jump in after maul. Or impale him proper, after cutting his legs off. Then he could have died, and the universe would have been better off for it.
But Maul wants to stay alive. Not based off of the choices he makes, the risks he takes, but in the way every animal does. If he had let go of his hatred, in the garbage pit of Lotho Minor, everyone would have been better off, But the instinct at the heart of all creature is to live, so Maul decided to live, at least until he could kill Kenobi.
It's so cruel, what the holocron's showed him. He asked for hope. Any hope at all, and he got Tatooine. Maybe the vision meant Skywalker-Maul figured it out easily enough after all, but what it lead him to was his death. The last hope for him, dying in the arms of the man for whom his hatred has sustained him-because of the terrible mistake he made, and because he could not hate his master. He finally got his warrior's death.
It was the only thing for him, you see. Because he was never the Chosen One. He never could have won the fight against Anakin Skywalker, and Maul might know that, or he might not. But to foil his master's plans would have been the best thing for him. And if not-at least he'd've got his warrior's death a few decades earlier then in canon.
