- Pokégym thread from Nov. 2006, also mentioning Mike Boozer, who started the rumors about the Prerelease Raichu.
- Pokégym thread from Mar. 2009 about the 10k sale.
- Thread from Nov. 2015.
- Thread from Sep. 2016.
- Thread from Apr. 2017.
- Thread from Jan. 2018.
- Thread from Mar. 2021.
- Thread from June 2021.
Knock yourself out with reading. 
As mentioned in a comment above, David Person aka dpersin1 owns a Prerelease Raichu, although I don’t think he showed it in a video or IG post yet (I could be mistaken?). He’s the #1 English Pokémon TCG collector (here a sneak peak at his collection where he shows the English trophies).
And also as mentioned above, there is another Prerelease Raichu for the Arceus set.
Before the endlessly looping discussions and memes are going out of hand: 
Greetz,
Quuador