"And from what I can see, you're trying to say there's actually no such thing as mental illness? LOL."
Well, I think what I'm saying is a bit more nuanced than that. There are behaviours and feelings that we can categorise as abnormal or disturbing or whatever you like to call it. For example, a friend of my partner's a few years ago started to display very alarming behaviours, including thinking he was a horse. He was diagnosed as having schizophrenia, and given medication for it, and now functions normally.
But my point is that "illness" is just a word we use to describe that. It's a convenient metaphor, but it's nothing more than a metaphor. With physical illnesses, we can describe accurately what causes them, the progress of the disease, and (in many cases) how to cure them. We can't do that with mental "illness". In fact, it's difficult to say what the thing we call schizophrenia, for example, has in common with the thing we call depression.
This is why the psychiatric profession finds it so hard to diagnose people: ask five different psychiatrists to diagnose a patient who is presenting with a particular set of symptoms, and they're liable between them to come up with three or four different diagnoses. Over the years, the manual that psychiatrists use to diagnose people, the DSM, has got thicker and thicker as more behaviours have become labelled as mental illnesses. The boundaries between what we regard as "mentally ill" and "mentally normal" have become fluid because nobody can accurately describe what we mean by "mental illness'.
There's a very good and thorough book on this by the clinical psychologist Richard Bentall, called Madness Explained, which challenges some of the conventional wisdom about mental illness.