Can one's mental health be so terrible that it's untreatable?

Hello. I am using my throw-away account, but the question I have put in the title is serious. Can one's mental health be so terrible that it's untreatable?

I have a lot of problems with myself and I suffer from them daily since I was little. And as I get older, it gets worse. I do not want to self-diagnose myself with anything, but I feel like there are a lot of things that are wrong about several aspects of my life. My relatives and friends directly suggest me to go to a specialist, not in a mean way, but I can see that they worry about me.

I am aware of my state, but I just start thinking about the number of things that bother me, and I feel like there's too much work to be done and it's near impossible for me to get better at all. If I went to therapy, I wouldn't even know where to start. I am afraid that I'd be misunderstood by potential therapist, or that I wouldn't be able to tell them everything that bothers me. The fact that I am prone to lie doesn't help at all.

Is it just my brain playing tricks on me, trying to convince me to not get any better? Once I have heard someone say that we suffer more in our head than in reality - and I genuinely can't tell if I am really that cursed, or just narrow minded. Can seeing a specialist not be help to some?