What I think is affiliate marketing only work for content creator i.e. someone who don't care with privacy.
It's not only for content creators. My friend created a casino review website years ago when the competition was very low and by just listing casinos and making simple reviews on his website, he was able to get thousands of affiliates and generated a lot of money. The competition is high today and the website market is saturated, for that reason, many people prefer to start a YouTube channel and get attention via content.
While we're in this forum are pseudonymous, although people can know the credibility and trustworthy someone's account, but it's not enough to reach "whales" and "addicts" to sign under your referral and gamble a lot.
There are types of people who don't click on affiliate URL and instead manually type the website that the affiliate shared with them, this causes a huge loss for many affiliates.
To be frank, affiliate marketing in gambling niche might be the hardest to success except you don't mind to "scam" them i.e. gambling is a way to make money, I can get rich from gambling etc.
Not really, with good SEO and ranking, it's easy to attract many people from search engines and sign them up under your affiliate URL. Today not only affiliates but everything is hard online because the market is very saturated.