Traditional sportsbooks have your address, your phone number, your email address, and more info about you. Some sportsbooks sell your information to list creators. Those list creators sell the info to tout services that call you to get you on board with their plans.
Well, apart from Web 3 casinos, other online casinos also request for customers original details during registration and KYC verification, just as the traditional casino would also request those details. Cryoto casino that allows gamblers to use the casino without knowing their original details is only on Web 3. There are some regulated crypto casinos or shady crypto casinos that can actually get customer details and sell them to scammers, or the casino could either be hacked and customer details could be leaked.
We have to play safe in everything we do, gambling is for fun and we should not only go after the fun leaving our privacy behind, as you have pointed out, we cant afford to make use of the gambling platform that will be a total discomfort upon us since we know that whatever information release to them are not hundred percent safe, they can decide on doing anything with them at their own pleasure or convenience while at our own detriment.
No reputable casino would want to sell customer details to scammers. First, such an act is going to tarnish their image; second, they will lose a lot of customers; and third, they're already making lots of money and therefore would not just sell off customer details for some cheap offer. The thing is that it is only a non-reputable casino that can trade customer details for extra profit, and that is why it is necessary to always make a choice for a good casino.
When it comes to reputability among companies, it is always relative, we can't say that a reputable company can't do a thing with 100% assurance, we should only vouch for ourselves and give them some degree of doubt regardless of what we perceive them to be. A lot is happening underground in companies that you may not know, and if truly a company is reputable, are their employees? Bad actors could be found in the sanest environment, they are just desperate for the benefit. That is another angle I like you to view it from.
I know a few companies they've called out in the past in this regard despite people believing they are reputable, and in most cases, the employees with that responsibility may be sacked or changed as the case may be after investigation, but has the deed not been done already despite the management are innocent? There are also individual cases that are secluded when the customers are persons of interest. For these, we should always know that our data are no longer private when shared so far it is human beings we are dealing with.