If the casino owner finds out that a referral is being abused, they can tell the person who spread the referral that it was wrong and warn them not to do it again. If they are still repeating it, the casino team may freeze their account until they understand their mistake. Gamblers responsible for spreading those referrals will surely know how to spread referrals properly so that they can get new people to click on those links and join under them.
If the referral link is misused it can be fatal for affiliate accounts and other accounts that register via the referral code, so the team can detect abnormal activity and can work to update new referral links.
Competition in the gambling business is indeed very tight, and players who spread affiliates will choose a casino that can provide benefits for them. And if they can get some extra income from affiliates, they will keep trying.
Online gambling has grown rapidly since the covid-19 pandemic so that the habits of gamblers have changed to online gambling modes and can enjoy more gambling games. Some skilled gamblers create content to share in the gambling community, so it will help them to earn extra income from sharing referral links.