David Chaum - He visualized a token currency which could be transferred between individuals. Chaum developed a so-called "blinding formula" to encrypt information passed between individuals and later, founded DigiCash.

Wei Dai - In 1998 Wei Dai proposed an "anonymous, distributed electronic cash system" - In the B-money system, digital pseudonyms would be used in order to transfer currency through a decentralized network. Satoshi referenced elements of B-money in his bitcoin whitepaper.

Nick Szabo - Bit Gold came with its own proof-of-work system that in some ways is mirrored by today's bitcoin mining process. Bit Gold aimed to avoid reliance on centralized currency distributors and authorities. Szabo's aim was for Bit Gold to reflect the properties of real gold, thereby enabling users to eliminate the middleman entirely.

Adam Back - He published a paper detailing his protocol in 2002, named: ‘Hashcash – A Denial of Service Counter-Measure.’ Hashcash used a proof-of-work algorithm to aid the generation and distribution of new coins, much like many contemporary cryptocurrencies.

I have had many silent thoughts on this matter and I contemplated the outcome of this experiment, if Satoshi decided to reveal his true identity. How many people would actually take him to court for intellectual copyright infringement? Companies like PayPal revolutionized person-to-person payments online and they might even find a reason to sue him.  

                           Is this not one of the reason why Satoshi Nakamoto never revealed his true identity?

Sources :

https://www.investopedia.com/tech/were-there-cryptocurrencies-bitcoin/
https://btcmanager.com/the-history-of-bitcoin-part-1-what-is-hashcash/
https://en.bitcoinwiki.org/wiki/B-money
https://en.wikipedia.org/wiki/Nick_Szabo