have co-opted it.
At its most basic level, the tweet is a reference to a scene from the 1999 movie 'The Matrix,' in which the character Morpheus tells the protagonist Neo that he has been living in a computer simulation and is given the choice of taking a red or blue pill. "You take the blue pill, the story ends, you wake up in your bed and believe whatever you want to believe. You take the red pill, you stay in Wonderland and I show you how deep the rabbit-hole goes." (It's worth noting thatMusk does seem to believe there's a good chance we're living in a computer simulation.)
But taking the red pill, or being "red-pilled," is much more commonly used on the internet to denote a right-wing political awakening. It's often used in forums dedicated to topics like Donald Trump or "men's rights" organizations.
It grew in popularity thanks to a subreddit called TheRedPill, which is openly misogynistic. Writing about in 2013, Business Insider described the subreddits views:
Welcome to The Red Pill, an Internet community on Reddit founded on the general belief that women have it better than men. Red Pill is not a dating advice bulletin, but rather a forum for people men, mostly exploring an ideology that revolves almost exclusively around gender. Those who "swallow the pill" maintain that it's men not women, who have been socially disenfranchised. Feminism is considered a damaging ideology and Red Pillers are quick to cite examples that bolster their points, some going so far as to argue that society is outright anti-male.
https://www.businessinsider.com/elon-musk-tweets-take-the-red-pill-what-it-means-2020-5