Dennis Hope started the Lunar Embassy Commission and starting selling plots of land on the moon that he didn’t own and that no one will ever be able to claim. He sold 2.5M acres.

https://en.wikipedia.org/wiki/Extraterrestrial_real_estate#:~:text=Dennis%20Hope%2C%20an%20entrepreneur%20in,(US%2450%2Fha.

Also, runner up selling insurance in the USA for alien abduction!!