Still alive, kicking and making millions
Just a lot of people believe in the same fiction and hence it appear real because of reinforcement learning.
Some take the fiction too seriously and get a pride from believing in the great fiction they live. Some push it extreme and die for the fiction.
If you claim sovereignty over a state's territory, violate its laws, refuse to pay its taxes, and threaten its citizens will violence, will the state respond?
If their response is severe enough to bring you into line, the state exists. If not, then the state is fiction.
"...a local Indigenous population that for some reason loved British colonizers,"
Grifters don't really have to come up with a truthful sounding story. They need to come up with something absurd.People said he was the best conman.