The US director was discussing his new movie, Ready Player One, at Comic-Con San Diego.
The film is an adaptation of Ernest Cline's book that depicts a dystopian world where humans take refuge in virtual reality in a world scarred by the effects of global warming.
Set in 2044, it entwines 1980s culture and futuristic concepts.
On reading the book, Spielberg said: "It was like the most amazing flash forward and flash back at the same time to a decade I was very involved in, the 1980s, but a flash forward to a future that I think is out there awaiting all of us whether we like it or not."
He described the world it is set in, where fossil fuels are depleted and extreme weather is pummelling the globe, as "so dystopic".
And virtual reality opens up the possibility of being able to do "anything you can possibly imagine", he said.
He added that he feared being "vilified for some kind of grand act of grand larceny of vanity" because so many of the moments in Cline's book focused on his own donations to culture.
Spielberg said he had to leave parts of his work out otherwise he felt he would have had to defer directing it.