Although the lectures are cut in some places, there are some parts that slipped [oops]!

From Audience: "Why do we need the 3rd Beit HaMikdash(Temple)?"

Rabbi Mendel Kessin:
"First of all the 3rd temple is the entire universe in that state of Tikkun (correction/rectification). So that reflects...It's the structure of the entire Briah[Creation] after the Tikkun.
And the second thing is that allows us to do the avoida of bringing corbanas (sacrifices)" [1]


Why is that? Because your existence is arrogance, as he teaches in another lecture:

Rabbi Mendel Kessin:
" 4 Levels of Gaivah [Arrogance]:

First I am it, everything exists for me.
Second lower form is egocentric, where everyone exists to serve me. [...]
The 3rd level of gaivah is no, you don't exist to serve me, but guess what, I'm superior to you. That's gaivah, but not as bad as the first two" [...]
But the 4th level of arrogance is much more subtle and most people don't realize that it's gaivah, it's arrogance. [...] and that's where Satan gets everybody basically, unless he's an incredible tsadik. What is it?
I am!!!! [...] That's called self-complacency, where I believe that I am and therefore I am entitled to do, to make decisions because it's for me! That's not to serve anybody!"
[2]

Sources:
Derech Hashem | The Presence Of God In Creation [1]
What Does Satan REALLY Want? [2]