Ego loss/ego death is pretty amazing, and it's a sliding scale. You could do too little of a psychedelic (most, not just DMT have this effect) and experience no ego loss, you could have some moderate ego loss, you could have near complete ego loss, and complete ego loss.
Shrooms being more easily dosed, I found that the ones I ate most often, 3 grams would give "near complete" ego loss.
So... my attempt to explain it?
For the sake of this explanation, your Ego is your sense of identity. It's the part of your consciousness telling you who you are, and explaining why you do the things you do in whatever way possible to prevent cognitive dissonance (conflicting beliefs).
If you believe violence is wrong, and you deck someone for upsetting you for whatever reason, your Ego is the part of you that says "Violence is wrong, but what I did was ok because X Y and Z". The stronger one's Ego in day to day life, generally the less humble you are. You're right, if someone disagrees with you, they're wrong, and whatever rationalization needed to make it that way is used.
My ego was never very strong to begin with, but ego loss has definitely helped me overcome some of my deeper seated issues.
The stronger the level of ego loss experienced, the more you forget "who you are" in a manner of speaking, and the less you defend the actions that don't follow what you believe to be the "correct" way to act.
I've found that the best "personality modification" happens for me at near complete ego loss on shrooms at 3 grams. I essentially look at myself as if I were another person, but still know it's me, and go "why the fuck do I do that, that's stupid... I should change that". No excuses, no rationalizations... just pure realization of the perceived fault as such, with a desire to correct it.
The one time I did 4 grams I don't have complete ego loss yet, but I'm too blissed out to care. The two times I've done 6 grams... there is no I, Me, Myself... just awe, amazement, love for everyone and everything.
---
Now, in reference to DMT... honestly the ego loss there seems far less useful in a therapeutic personality modifying sense... but it does give a very spiritual feeling. The breakthroughs I've had, the only concept of myself was the fact that I was witnessing something so incredibly amazing that nothing else mattered. I was insignificant... but blessed that even as such, was where I was at. Best way I can describe it for DMT.