If there are multiple faces of truth and anything you believe can be reality(as told by @Chinmay) in this Universe somewhere then will it be wrong to say that “Nothing Matters”.
Because believing in “Nothing Matters” also lead directly to soul i.e. when mind stop caring about what is outside and focuses completely inward to himself.
Further, isn’t “Knowing thyself” mutual to knowing “Nothing Matters”?
Also think about “Does Moon really exist when you close your eyes?”
https://www.quora.com/Does-existence-depend-on-conscious-observation