Casino and gambling websites have contributed big time in the growth of bitcoin. I read an article about it long time back about it and below is the link,
https://news.bitcoin.com/bitcoin-gamblers-wagered-4-5-billion-btc-2014/Remember, the article was written back in April, 2017 and since then, the number of crypto websites have increased many fold as well as the number of crypto users have seen new heights! The 4.5 billion USD has now crossed well over 10 billion USD, I assume!
Cryptos have actually opened up a new world to the gamblers worldwide! Earlier, it was a pain to transfer money from foreign bank account to the gambling account. It used to take more than a day along with an exorbitant fees. Cryptos have paved the way for new funds in this sector while increasing its own adoption rate due to the super convenience it provides to the gamblers!
I believe, online gambling is probably the only major business sector, which has used cryptos the way it has to be used! Not as an investment, but as a currency!