All promotions will go to nothing if the casino does not have fair and accommodating customer service. After you attract players to your platform, the next thing to do is to make them stay, which the casino can do through their games and prizes, and the players will trust the casino more if their concerns are properly addressed.
Many complaints by players to the casinos they are playing are due to miscommunication and a lack of sympathy for the players' concerns.
The casino in particular in this situation and company in general, will spend money for nothing and only get lessons for themselves back. Users will get most benefit from bad marketing and perhaps they like it, but with company it will cost them more while like you said get nearly nothing back.
To run it well and get good effects back, they must plan many things beyond marketing. As they must have good products or best new products to release together with a marketing program, and good terms in their program so that they can filter cheaters well but keep their assessment more lighter in world load, and more importantly to avoid any harm on their business reputation, if better increase their reputation through marketing.
In general, online gambling interest is currently dominated by young people where those aged 20 to 40 years are of course easier to reach to attract their interest by advertising it on various popular media platforms such as Facebook and Twitter or currently X.
It's because old people have difficulty to use Internet and digital devices than the young, but the elderly can be gambling addictive in their own ways like in physical casinos than on online casinos.
It's natural change in society as population demographic changes with time and generation by generation while technology innovation brings many new things to the young that are more adaptive than the elderly. For example the young generation are more adaptive with cryptocurrency and blockchain while the middle aged people and the elderly nearly less or don't care about joining.