Why do you read guro? Do you view it as porn or do you read it ironically? Do you have violent fantasies or is it because guro is typically drawn and not actual smut?
I don't, but it's probably the same reason why other people get into kinky ass shit. Either it's some naturally developed kink from a past experience, or the need for more depraved shit to get stimulation if they're too used to vanilla stuff.