Many of really successful affiliates leave money on the table as they don't understand the value of domains. If you are making $100k per month that doesn't mean it is your maximum. For example, someone took MyReallyCoolBrandableDomain.com for $8 and use it for his website which makes $100k per month. Although he is doing great, I am 100% sure he would be making more if he took KeywordFull.com domain name and do everything exactly the same. EMD would rank better (100% sure, if everything else is completely the same), at least for the keyword phrase in domain name. This could mean hundreds of clicks more per day, and automatically higher profit.
The other thing is trust. Once you build your brand it is the same (regarding trust) if you own Casino.com or bWin.com, but when you are unknown I am sure 99% of people will deposit on Casino.com rather than bWin.com (if both sites are of the same quality).
It is the same in other niches. Lets say you want to pay for insurance online and you came across Insurance.com and Insurcoo.com. It is no brainer to whom will trust the majority of first time visitors.
Nobody can tell me that bWin.com, Bet365.com or Ladbrokes.com are better domains than Betting.com. Yes, you can achieve global success with LadBrokes.com or Cooldoooo.com but if you do the same web and
SEO development with Betting.com it will be quicker, easier and more profitable. BTW, I don't see any reason why Betting.com could not be a brand, together with the extension.
For starter, Casino.live is much better than any brandable domain.