The Sudden Savant Syndrome is a rare phenomenon in which an otherwise normal person gets some kind of brain injury and immediately develops a new skill. The linked article tells the story of a 40-years old guy who banged his head against a wall while swimming, and woke up with a huge talent for playing piano (relevant video). Now, I've spent 15 years in formal music training and I can ensure you that nobody can fake that kind of talent without spending years in actual piano practice.
Here's the story of another guy who banged his head and became a math genius better with math; you can find several other stories like that. And maybe most puzzling of all is this paper, describing a dozen cases of sudden savants who didn't even bang their head, and acquired instant skill while doing nothing in particular.
I vaguely remember one sudden savant story being mentioned on a children book by Terry Deary, presented in his usual "haha, here's a funny trivia" way. But even as a child, I was pretty shocked to read that. Like, seriously? You could become a math genius just by banging your head on the wall in some very precise way? The concept lurked in a corner on my mind ever since.
I don't think that Sudden Savant Syndrome is just a scam; there are too many documented cases and most kind of talent are very, very difficult to fake. But if true, why there are so surprisingly few studies on that? Why is no one spending billions of dollars to replicate it in a controlled way? This is a genuine question; I know very little about biology and neuroscience, but it surely sounds way easier than rewriting the genetic code of every neuron in the brain...
Have you ever played piano?
The kind of fluency that we see in the video is something that a normal person cannot acquire in just a few days, period. Even if he didn't literally play perfectly the first time, playing perfectly after one month would still be incredibly impressive. You plain don't become a pianist in one month, especially without a teacher, even if you spend all the time on the piano.
Also, this guy is apparently still not able to read sheet music and still doesn't know anything about music theory. It's difficult to explain in non-technical terms, but his music is exactly the kind of music that I would expect from an incredibly talented person who knows nothing about music theory.