Why is it so hard for people to accept the fact they need help?

I've just been wondering why it's so difficult for some people to accept, or even believe, that they have issues to deal with, just like everybody else. One of my mom's friends is a hoarder, and from what I've been overhearing, while she seems willing to accept the fact she needs help, she refuses to acknowledge that she actually has a serious issue with throwing things away. It's gotten to the point where she even dumpster dives while walking her dogs, and just hauls it all into her apartment.
Edit: And I know it typically stems from emotional or other issues, but that doesn't change the fact I'm still confused about it all as a whole, just clearing that up!