A domain name like bitcoin-gamble-casino782.com would be pretty bad because its hard to say hard to remember and is not very memorable.
What matters most in a successful gambling site is the service and the track record of trust between the company and its users.
People trust stake and primedice because its owners track record not because stake.com is a one word on topic domain name
Indeed, most important thing in developing a startup is customer trust, where developer must first build customer trust. For me domain is also important because it will build their company's brand later, right domain selection is by using 1 or 2 words, relevant to company that will be built, not using special characters, and if possible the domain is a well-reputed aged domain ( this can improve their site on search engine).
Trust me, if you have the best domain name and your site is like shit,,, you will lose a lot of money and have no business. But on the other hand, if you have a rather average domain name but your site is awesome,,, everybody will know your site.
Look at 1xbit. Kind of a rater shitty name but they got so famous even though they were a scam site and people all knew about them.
or sealswithclubs;)