Its easy to think of becoming successful in affiliate marketing with youtube channel that has lots of subscribers, it could be possible. In reality, its not easy. I personally have been there which is why podcast are much better and many have been successful with just choosing a trending topic and discuss it with a guest. However sticking to a particular niche like casino can't be get that much audience.
This is possible, but when we see the one successful youtube channel, we don`t see thousand of the same channels which have no subscribers ever and no one talks about it.
And the same time you need to work hard every day to create new content. If you stop - your channel lose subscribers every day. And the profit falls down every day too.
And in general, it is extremely difficult to maintain channel traffic at a level that gives at least some tangible income. I think there are already millions, a whole army of people disappointed in this type of business, who spent a lot of their time and received nothing in return. Also, the popularity is so changeable that today thousands or tens of thousands of fans look at you, and tomorrow you are forgotten and only a hundred fans are still with you. I would not advise anyone to start doing this kind of business now. Because the chance of success is 0.01%, and you will spend a lot of time and money.
And in special topics, for example, like reviews of crypto casinos, the chances are generally negligible.