So I think I now know what Ni is like when its used.
Its seeing the whole picture at all times. Both sides of the same coin. When someone says they are "Strong Willed" that also implies that they are "Stubbornly narrow sighted." If someone says they are "very shy" it also means they are "good at keeping secrets." If someone says they are a psychopath, another may argue they are "willing to do what others are not."
For every bad there is somehow a good. A yin and a yang.
And when you use Ni, you see all of existence in your mind. Civilizations flowing, coming and going, mountains forming and crumbling, cultures forming and spreading... and in the end the Ni dom (INTJ INFJ) is left feeling small, wondering how its possible to do anything good in such a huge world. (many INFJ's type as enneagram 4 scared of being insignificant, and many INTJs type as 3 or 5, scared of being worthless or inadequate.)
When I use my Ni I see everyone around me as equal to me, but I also see myself as having some kind of a gift. The ISTJ who acts like a badass and tells everyone how tough she is, does so because she feels no one respects her. So I will give her this respect and as a result she will give me something in return, perhaps she will get along with me or protect me or help me in the future. The ENTJ asks a lot of questions and constantly seeks knowledge, may secretly feel stupid because he doesn't actually understand himself, and believes understanding the world will bring about understanding of himself.
With this seeing 2 sides of every coin, Ni doms also tend to be indecisive, as all "truths" are equivalent. Their indecision comes in many forms, either in the moment decision making (INFJ), Being able to decide if one is good or evil (ENFJ's are too ethically objective with Fe dominance), being unable to choose one morality over the other (ENTJ's are too objective with Te dominance), and being unable to take action due to fear of equal and opposite forces of the universe (INTJ). Many Ni users (or intuitives for that matter) may feel depressed because... What's the point?