Undertale - Through Chara's Eyes

Not really, if you consider things for a moment.

Chara, before the start of the game, apparently disliked humans and grew fond of monsters. It's not without reason to assume they were mistreated at some point in their life, which drove them to coming to the underground.

Their plan before, was to kill 6 humans and take their souls in order to shatter the barrier. Asriel couldn't do it, and the two died due to the most effects of a monster trying to contain a human soul and human determination.

The entire character of chara being a murderous psychopath comes from the interaction with them in the Genocide route. But in order to get there the player had to force the human, and force by extension chara, to murder everyone first. Think about that a moment. The player force a character who sacrificed their life to try and free monsters, into killing everyone they loved and worked to free.

Who wouldn't be insane after that? Who wouldn't be a souless being with no value on anything after being forced to experience that?