All conscious functions are linked to the Ego (the technical term is "ego-systonic"). For many people, only the dominant and auxiliary functions have become conscious, but it is possible for a well-developed type to raise functions 3 and 4 to consciousness as well.
The danger arises when the Ego becomes too invested in a function (usually the dominant). I've been guilty of this myself in the past, insisting that other people's understanding of a situation falls far short of my own Ni clarity of vision. I've noticed it in Ti-users as well: they tend to become very dogmatic, nit-picking and extremely sensitive to any criticism (intended or otherwise) of their knowledge and pet theories (I call them "Technical Prima Donnas").
Although this can lead to conflict between dom-Ti types, it gets much nastier when egotistical Ti meets egotistical Ni. Ti keeps insisting on the "One And Only True Definition" while Ni counters with "All Definitions Are Completely Arbitrary" until it gets out of control and becomes personal. Then they start name-calling and abusing each other.
I'm not joking here, I've seen it happen both in real-life and on this (and other) forums.