I know there’s no way certain people are figments of my imagination, because there’s no way I could have imagined that much idiocy.

Jokes on you, because I’m shitting naked right now, and if I’m a figment of your imagination then you’re the one imagining it.

Well you didn’t exist before last Thursday.

the captain explained: “Hitchcock snapped out of it for a minute or so. He was alone. He climbed into a space suit. He opened an airlock. Then he walked out into space—alone.”

Clemens blinked through the immense glass port, where there was a blur of stars and distant blackness. “He’s out there now?”

“Yes. A million miles behind us. We’d never find him. First time I knew he was outside the ship was when his helmet radio came in on our control-room beam. I heard him talking to himself.”

“What did he say?”

“Something like ‘No more space ship now. Never was any. No people. No people in all the universe. Never were any. No planets. No stars.’ That’s what he said. And then he said something about his hands and feet and legs.

‘No hands,’ he said. ‘I haven’t any hands any more. Never had any. No feet. Never had any. Can’t prove it. No body. Never had any. No lips. No face. No head. Nothing. Only space. Only space. Only the gap.’”

The men turned quietly to look from the glass port out into the remote and cold stars.

Space, thought Clemens. The space that Hitchcock loved so well. Space, with nothing on top, nothing on the bottom, a lot of empty nothings between, and Hitchcock falling in the middle of the nothing, on his way to no particular night and no particular morning. . . .

https://en.wikipedia.org/wiki/The_Illustrated_Man#No_Particular_Night_or_Morning

What makes you think that you aren’t a figment of your own imagination?

No you