'Many crypto experts have noticed that Bitcoin’s choice of secp256k1 elliptic curve was unusual for its time, as it was not yet well researched. ... Cointelegraph asked one of the world’s leading cryptographers, Tatsuaki Okamoto, about this unusual choice. Okamoto currently serves as director of the Cryptography & Information Security Lab at NTT Research. According to Okamoto, there are two alternative explanations for this choice: Either Satoshi picked because it offers greater efficiency or because it may have offered a secret backdoor.'
https://cointelegraph.com/news/this-researcher-says-bitcoins-elliptic-curve-could-have-a-secret-backdoor
'Laszlo Hanyecz, who worked closely with Satsohi in 2010, told Cointelegraph that he was befuddled by Satoshi’s choice of the elliptic curve secp256k1. The use of this curve, at the time, was unusual. ... At some point, Hanyecz sent Satoshi an email asking him why he picked this particular curve, Satoshi explained to Hanyecz that he had had some experts helping him: “‘I had a bunch of people look at it and they told me this was good.’ And he didn't really elaborate on it, but he said he had experts look at it.” It is not clear exactly when Satoshi sought this outside help, but prior to launching Bitcoin.'
https://cointelegraph.com/news/satoshi-nakamoto-had-outside-cryptography-help-says-early-bitcoin-dev
I had a bunch of people look at it and they told me this was good.