Major Sportsbooks and Betting Brokers that are used by bigger professional players started accepting Bitcoin as a payment system these last months!
Pinnaclesports is one of the biggest online sports books in the world and the market leader when it comes down to low margins. Bitcoin is not yet shown on the bottom of their main page where all the payment options are shown, but it has been added on their payments options page. Betting in bitcoin itself is not supported and they are using bitpay to process the deposits and withdraws on their website. All deposits and 1 monthly withdraw are free (extra withdraw costs 12€).
(All terms and conditions for Pinnaclesports Bitcoin Payments)
Sportmarket are an European based betting broker service I use myself who allow you to have accounts at many different big bookmakers (Pinnacle/SBO/IBC/ISN/...). They announced near the end of last year to be accepting Bitcoin Deposits and Withdraws. They do charge a 1% deposit and withdraw fee similar to what they charge for Skrill and Neteller and use xe.com for the exchange rate.(All terms and conditions for Sportmarket Bitcoin Payments)
Asianconnect are an Asian based betting broker I've used in the past. They provide for accounts at the bigger asian bookmakers along with an all in 1 solution where you automatically take the best available odds similar to Sportmarket Pro. Not much information is shown on their site about it aside from the fact that deposits and withdraws are free of charge.(All terms and conditions for Asianconnect Bitcoin Payments)
This is great news for Bitcoin and cryptocurrencies in general as many of the Sports Betting Whales can now also use Bitcoin as a way to fund their betting activity. I have not used it myself but likely will in the near future to maybe put some funds safe during a bear market or convert some of my bookmaker funds that are used as a buffer into bitcoin after a big correction.