We have a kaballah to rely on for proof that HaShem created the world and isn’t just playing tricks on us.
So you claim. Who says the idea wasn’t planted in your mind to make you a docile battery?
What’s the difference between the world existing and us believing that it does?
Nothing. Since the world is only a “Yesh” as long as the Ribbono Shel Olam decides to keep it that way, it makes no difference whether we actually exist (as the beings and entity that we see) or not.