Beyoncefan666 made some outrageous true predictions including brexit, trump, katie perry and Beyonce.
Its all there for you to see. The predictions are precise and made months in advance.
How did that person do it on twitter?
Context for others:
So I’d never heard of this, but the very first hit on Google for the name not only gave a description of these “predictions,” but gave a fairly reasonable account on how it was done. That is, the account was set up as a private account, a whole bunch of tweets were made with all sorts of predictions, and then the incorrect ones were deleted, and then the account was only publicized after it had several correct predictions under its belt, so to speak.
This prediction trick has been around much longer than Twitter.
This comes up fairly frequently here in Kentucky due to the popularity of horse racing. The con artist makes mass horse racing tips to many people. He only continues to contact the people to whom correct predictions were given. Then asks for money for his ‘tip’ for the next race.
In fact, it was discussed at least once here on the dope: What’s the name of this mail fraud con?
This was going to be my guess, as well. I figured out this con on my own back in high school, only to discover it was hardly an original idea. This is just a modern take of the same idea.
Retroactive forecasting is sooo much easier. 
Once their follower count gets large enough the penny stock tips should start flowing.
A previous thread on the raindrop con, which in turn links to another …