It laid the philosophical and technological foundation for Bitcoin.

A free-market, non-state digital money had long been the Cypherpunks' ultimate goal.

They—and others—made numerous attempts, but none of them worked.

These failures would not be in vain. They provided crucial lessons and building blocks that would lead to the birth of Bitcoin.

Here are some noteworthy examples:

In the early 1990s, Cypherpunk David Chaum tried to take public-key encryption and apply it to digital money with DigiCash. After struggling with adoption and regulatory problems, the company behind DigiCash went bankrupt.

E-gold was launched in 1996. It was an innovative attempt to create a gold-backed digital currency. However, the US government shut it down and indicted the business owners on money laundering charges and operating an unlicensed money transmitting business.

In 1997, Cypherpunk Adam Back created Hashcash, a proof-of-work system designed to combat email spam. The idea is to impose a computational cost on certain activities to deter malicious behavior. While Hashcash didn't gain widespread traction, its core proof-of-work concept became a fundamental component of Bitcoin.

In 1998, Cypherpunk Nick Szabo proposed Bit Gold as a digital currency that relied on cryptographic proof instead of trust in a central authority. "Unforgeable costliness" is one of Bit Gold's foundational principles. Provable costliness refers to the idea that a certain amount of computational work—or cost—must be verifiably expended to create a new unit of the digital asset. Bit Gold was never launched and remained a theoretical proposal.