Here's why:
* "Self" is typically used in combination with other words to describe something related to oneself, like "self-esteem," "self-reliance," or "self-centered."
* "Hearted" usually refers to someone's character or disposition, like "kind-hearted" or "big-hearted."
It's possible that "self-hearted" was intended to convey a specific meaning, but without more context, it's difficult to say. If you can provide more information about where you encountered this phrase, I might be able to help you understand its intended meaning.