As someone who talks and writes about psychic phenomena I often see or hear the words in conversations, "nuts" and "crazy" online and off. To me, "insanity" and "nuts/crazy" are different concepts. I won't use dictionary definitions but more what I see as common parlance. "Insanity" is a legal term. To me, I understand it as "dysfunctional and incapable of understanding right/wrong, incapable of living within legally accepted norms". On the other hand "nuts/crazy" are words we use to describe those who simply don't fit in.
I have a t-shirt on one of my stores that reads "Everyone is someone else's weirdo".
Everyone is odd or different from someone else's point of view. So are we psychics "nuts/crazy"? Yeah. If you are uptight, anal, overly obsessed with fitting in (laugh) ... which makes you "nuts/crazy" from my point of view. There is no such thing as "nuts/crazy". It's a value/ego judgment with little real meaning. In my opinion most of us are afraid of being "nuts/crazy" because we don't want to be different. We're not so much afraid that we might be mad, we're afraid that we'll get bullied.
No one can bully you with the "nuts/crazy" label unless you choose to own it. A long time ago I made myself comfortable with the idea that some people would doubt my experiences. I let go of needing to "prove" anything. If you doubt yourself, start keeping a journal. If your insights, visions or dreams are right more than 50% of the time, there is some objective evidence that your experiences are psychic. You won't be infallible, but you can learn to use your intuition to improve your life.
A little skepticism is a healthy thing. It doesn't have to carry the "nuts/crazy" stigma if you are wrong on occasion though. I think we all do this to ourselves during the occasional fallow times where our intuition seems to dry up. After a while you get used to the fact that sometimes psychic ability waxes and wanes. That's normal.
Somewhere in between "nuts/crazy" and "insanity" is mental illness. To me this is a wide range of both physical brain disorders and assorted thinking dysfunctions. No doubt some of us have suffered from mental illness at times. Most of us have. Depression is a mental illness. I've suffered from depression in the past. Quite serious, long-term depression. I've gone through trauma and suffered PTSD. I wager that just about everyone has some form of mental illness at some point in their life. We have to get rid of the stigma here, or we won't be able to address it when it really is a factor. Mental illness isn't always permanent, it is often easily treated. There are both cognitive and medical treatments that are effective. What is "crazy" is refusing to seek help because you are afraid you might be "nuts".
Any time you have strong psychic experiences, voices in the head or strange compulsions, and physical sensations or symptoms like headaches or dizziness, your first step must be to rule out a physical cause. So I'll often recommend that you see a doctor. I'm not a physician, and it is legally and ethically required that I refer you to a doctor, even when I don't really feel that's necessary. I will suggest you be discrete what you decide to share. Find out your doctor's attitudes towards psychic experiences before you share any "voice" experiences. If you are leery, there may be good reason. If their attitude is hostile, see another doctor. Don't see a doctor you don't trust.
Generally speaking, if you hear voices and they are positive and you find that the information they give you is accurate more often than not, you are probably a channel. If they are hostile, there is pain, they persist even after being told to leave, or the experiences are causing havoc in your life, then get to a doctor and be fully honest with them. Even if it is something psychic, and not true mental illness, you need a counsellor who can help you sort out some boundary issues. Healthy, balanced people don't pick up negative entities as easily as those who have emotional or mental challenges. You may be fully sane in the clinical sense of the word, that doesn't mean you won't benefit from some professional guidance.
Having a diagnosis of mental illness doesn't mean that your experiences aren't objectively "real" either. I think this is another big fear I commonly see. People become attached to their entities, to their experiences, and even when they are scared silly, to the drama of being in the middle of this kind of experience. They don't want to be told that it's not real. I've learned that just because one may be mentally ill, it doesn't mean they aren't also psychic. In fact it is a common observation that schizophrenics are often strongly psychic.
In the end, if you are afraid, you have to drill down deeper. What is it you are truly afraid of? Is the fear even an issue? Are you addicted to the drama? That's what's really "crazy" in people for the most part. Accept your abilities, make a resolution to step past your fears, and you will find in 99.99999% of cases, that very quickly things calm down and you will find that what used to scare you is a source of great value and insight.