Hal Finney helped invent modern encryption, an essential part of Bitcoin. The actual idea is straightforward, but the code surely required borrowed talent. I believe most of the code had a single mastermind, but was somewhat pieced together between 2-4 people... and open-source. Remember the twin-primes conjecture was partly solved by a then basically unknown individual in the math world, and his paper was extremely technical.
Therefore, please consider that brilliant people and groups exist without being known by the scientific/university community. (As for me I literally cannot even spell brilliant at this moment. Hah.)
One more thing, I do not believe S. Nakamoto is still alive.
It is very possible it was a reclusive genius or group of them.