Why does Chang 'e live on the moon?

It was recorded in the early days that "Chang 'e took the elixir of the Western Queen Mother, and last month was the essence of the moon", which meant that Hou Yi asked the Western Queen Mother for the elixir of life. Chang 'e stole the elixir, ate too much (both husband and wife's share), became a fairy, ascended to heaven, but was punished as the ugly toad who smashed the elixir in the moon palace.