Bitcointalk, for as long as I've been here, has been full of gamblers and gambling is and has been one of the biggest uses of bitcoin I know of
It's kinda funny: the VCR was made popular by porn, for Bitcoin it's gambling.
First Bitcoin gambling website is SatoshiDice.com but now it is Bitcoin Cash gambling site.
When that site accepted Bitcoin for gambling, it made big effects and brought more people to Bitcoin blockchain.
Bitcoin history book, page 101.
Besides developers contributing to the Bitcoin-Qt client, others were busy creating innovative use cases for Bitcoin. Code developer
fireduck (registered on BitcoinTalk on 29th April 2012) created a ‘Bitcoin Casino’ website in early April 2012. On 17th April 2012, he posted on Reddit:
“I have been running a bitcoin casino for a little over a week. It has made 146 BTC with an investment of around 45 BTC to get it started. I don’t want to run it any more because I am concerned about legal issues.
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The casino website became known as SatoshiDice soon after it was sold to Erik Voorhees. The domain address
www.satoshidice.com was registered
on 18th April 2012. Erik Voorhees announced the blockchain-based betting game on BitcoinTalk on 24th April 2012.
Within weeks, the game was responsible for at least half of all BTC network transactions.