Some people will say something like what if "this" is all just a dream?
Ok... but then it has to be "someone's" dream.
Some people will say that what if "this" is all just a video game?
Ok... but then it "someone" has to be playing the game.
Some people will say nothing is real
Ok... but "we" are experiencing something, so even it the material world is an illusion, there has to be some immaterial world... some spiritual world... some higher supernatural universe were "we" or "I" or "god" exists.
Even a hallucination is based on something... drugs, neurons, something... sure the hallucination might not be there, but someone is there to experience the hallucination.... even if "it" is all just one consciousness that is having all of these "experiences"... there must be at least one... otherwise there would literally be nothing and no-thing to experience.
Yes, during Lockdown over here, and even before, I delved into the thought of the 13th century zen master Dogen. Zen is not my home ground, I'm very much "Pure Land" where the heart of what practice there is is around the kitchen sink, rather than hours upon a zafu. But I found a lot to reflect upon with Dogen, he seemed very "modern" to me.
Dogen said that "for to be is to understand, that is, one is what one understands."
An aspect of this, for those who like this sort of thing, is Dogen's non-dualistic analysis of reality, where he investigates the "difference" between our dreams and our waking state, between illusion and reality. In a sense, Dogen says, there is no difference! Thus, "all" is illusion, unreal. Yet if so, all is Real, whether dream or reality.
Which very much simplifies things. "In the whole of the universe there us nothing that is hidden".
Well, maybe enough.