The answer is … he was just really, really mad. Yes, really.

It was revealed in Star Wars: The Clone Wars that after being split in two, falling down a giant hole, and being dumped in a landfill, Darth Maul survived “by focusing on his hatred of Obi-Wan Kenobi.” According to StarWars.com, the Sith apprentice was so traumatized by the experience that for a long time, he forgot who he was.

Source: https://www.distractify.com/p/how-did-darth-maul-survive