The Universe Does Exist

" there exists nothing except God, may He be exalted, and this existent world...it necessarily behooves one to consider this existent as it is..." (Moreh Nevuchim 1:71)

"the foundation of the whole Law is the view that God has brought the world into being out of nothing..." (Moreh Nevuchim 2:30)

It is clear that the Rambam is teaching that the Universe exists and that we may not associate it with Hashem. In halacha, associating Hashem with any physical object is a Torah prohibition known as "shituf".

Rav Meir Triebetz has posted on the hashkafacircle.com website a group of shiurim explaining in detail the viewpoints of the Vilna Gaon and the Leshem, both of whom built their philosophy on the Rambam's Moreh Nevuchim. If I understand those shiurim correctly, we must believe the Universe actually exists and is not "Godliness" as some radical Kabbalistic or Chassidic doctrines claim.

This prompts my own question: Is radical "Kabbalism" a philosophical dead end for Jews?

For example, in the apparently Chabad influenced video linked below, the speaker claims (around 1:10 min.): "In reality we don't exist". https://www.youtube.com/watch?v=3bZBAHuOQHE

I believe this is a doctrine well accepted in Chabad circles, as I have heard it stated by a number of serious Chabad people. However, the claim that "In reality we don't exist" blatantly contradicts the first verse in the Torah that states that Hashem did create the Universe.

If one truly believes "In reality we don't exist", then how can one believe in the first verse of the Torah or that a Torah even exists?

How can such a person believe that "non-existent" creatures are obligated to perform mitzvot?

How can such a person believe there is an "olam habah"?