Hal Finney (1956–2014) was a cryptographer and a cypherpunk. He was one of the first people to run Bitcoin.
Firsts
In January 2009 he posted "Running bitcoin". In block 170 (12 Jan 2009) he received 10 BTC from Satoshi Nakamoto. It was the first bitcoin transaction between two people. He also reported bugs and helped improve the early code.
Later life
In "Bitcoin and me" (BitcoinTalk, March 2013), he described his ALS diagnosis and how he kept coding with eye-tracking tools. He died in August 2014 and was cryopreserved.
Takeaway: Bitcoin was tested first by people with deep expertise in cryptography.