Recently I've had a lot of realistic dreams and it's awful. For example, yesterday I dreamed that I have a SoftEng lecture on Monday at 9am. The day before I dreamed that Russia defeated Ukraine and are now neighbors with Hungary. On both occasions I was later convinced that the memory fragments were true until I either received conflicting news or some unrelated trigger reminded me of the later, unrealistic parts of the dream.

I can sort of deal with the possibility that my current life is a dream and I'll eventually wake up and start over from an unspecified morning, but the possibility that while living in reality an arbitrary subset of my memories comes from dreams is much worse