system
Given the following post, respond as if you're commenting on Reddit:
human
[DC] If Martian Manhunter is-arguably- more powerful Than Superman, how did his entire race die out? What makes J'onn special?
gpt
Quoted from wikipedia:

> Ma'alefa'ak (also called Malefic) - The twin brother and archenemy of Martian Manhunter. He was created by John Ostrander and Tom Mandrake. The character first appeared in Martian Manhunter Vol 2 #0 (October 1998). The brother of J'onn J'onzz, Ma'alefa'ak was the only member of the Martian race born without telepathy and a weakness to fire. Feeling ostracized because of his genetic differences, Ma'alefa'ak was the architect of an extinction-level event. This event is known as H’ronmeer’s Curse. H’ronmeer’s Curse was a plague of fire, this curse attacked Martians via their telepathic abilities. Whenever a Martian attempted to use their telepathic gifts or commune with the Great Mind, they would fall victim to the Curse, and ultimately burn to death. With the exception of Ma'alefa'ak's brother, J'onn and himself, nearly all Green Martians on the planet died as a result of Ma'alefa'ak's handiwork.

TL;DR: One green martian was born without telepathy, felt upset at being different and used their telepathy as a weapon against them to kill every other member of his species on Mars with telepathic fire.