What are 'we', what are you calling the world, and what is your standard of proof? The only thing we can really be sure exists is our own consciousness, because we are aware and able to question it. Everything else is only what we subjectively see projected through the vignette of our thoughts and our perspective. I can't prove that I am real to you, but as I sit here typing this I could stop at any point as a proof to myself that I have the freedom to choose. I could spell som3thing wrong on purpose. I could kill myself for no reason other than having the ability and the free will to decide to do so.
The question is, how can you prove to me that you exist? And how can I prove myself to you? We can't. There is no logical or empirical way for us to compare our experiences. I cannot share my perspective with you, and for all you know I might not even have one. I could be a philosophical zombie, a person without original thought, but replicating normal behaviour just out of primal instinct. How would you even be able to tell the difference? How can you tell if another person's thoughts are authentic?
We need not be living in a simulation for everything we see and sense to be maddeningly unreal.