Neuroscientifically speaking, we all experience our own custom hallucination all the time, and ‘reality’ is just the shared aspects of our hallucincations that we agree on.

https://www.theatlantic.com/video/index/577087/neuroscience-perception/

Or you can go the Taoist route:

“Once upon a time, I, Zhuangzi, dreamt I was a butterfly, fluttering hither and thither, to all intents and purposes a butterfly. I was conscious only of my happiness as a butterfly, unaware that I was Zhuangzi. Soon I awakened, and there I was, veritably myself again. Now I do not know whether I was then a man dreaming I was a butterfly, or whether I am now a butterfly, dreaming I am a man. Between a man and a butterfly there is necessarily a distinction. The transition is called the transformation of material things.”