Most times I don't have to blame the casinos because most gamblers who go for this bonuses don't even have the patience to read the terms and conditions before going for it because if they do, then they would have understood that it wasn't going to be an easy task.
Nevertheless, I would prefer that the casinos make this terms very fair and not extremely against the player.
We can't blame the casino but must check what we've done to know what happened. If a gambler wants to get a bonus from an affiliate, they really have to be able to convince people that the casino is good and can be a place to gamble. However, people think that sharing affiliate links can bring them a lot of bonuses but that's not the case. They can get a lot of bonuses if people who join under them use big money to gamble so the bonus will also be big. But if they don't, they won't get a big bonus or even get anything.
Mind you, there are still many individuals who earn a decent income by sharing affiliate links. In fact, it's considered a safer way to make money in gambling because you don't have to gamble yourself to earn money. Instead, you simply need to persuade people to gamble and sign up using the link you provide.
It will be more successful if you have a YouTube channel or any social media platform where you can attract your followers to gamble.
Anything that a person think they cannot earn with it since they are lazy or being shy to share their referral link think that its just a waste of time if they do that. Maybe they are not really interested about it and just share their sentiments to the people who can read their statement. But if they do a lot of efforts and share the links of legitimate casino's or other platform they can possibly earn decently with it especially if they can convince whales to register under their links.