Bitcoin was the first cryptocurrency to be ever invented in the history of internet. It started as a research paper back in early 2000’s by Satashi Nakamoto.
It was conceptualised and later released as a cryptocurrency in January 2009 when the first block of bitcoins were mined by the founder.
The users of dark web were the earlier adopters of this cryptocurrency due to its ability to make the transaction anonymous.
As far as my recollection goes, bitcoin was transacted under the tor network, a browsing tool which hides your online activity.
Surprisingly, the early buyers of bitcoins were drug buyers/sellers and all sort of criminal syndicates. Drug consumers from silkroad were able to purchase 3000 bitcoins for a mere $200.
There were other people who bought bitcoins for research purposes, one of them was a guy named Koch from Norway who bought 5000 bitcoins for $27.
There are many people who accidentally became millionaires due to sudden surge in value of bitcoins.
A very detailed illustration of the history of bitcoin is provided below