I do not think that it is to attract addicted people to gambling but more about how if you start gambling once and have fun, you remember how fun it was and keep gambling some more, even if you are not addicted. I am not addicted to gambling at all, there are periods in my life when I go months without gambling (unfortunately not anytime soon) but what happens is that I end up gambling for free just a bit, then deposit a bit, gamble with that too and then stop again, which obviously means I am not addicted since I can stop that easily, but I do not remember a single time when I used free bet but then never invested any money at all into gambling some more on top of that before I stopped.
Of course, everyone has a different kind of understanding, mental capacity, money management in both personal life and gambling.
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You are just a rare gambler who knows his limits and control the urge not to lose more than you can afford.
agreed with @seleme, maybe you are a rare gambler and an exceptional one. No man becomes addicted overnight. At first, they play for fun, then the hobbyist plays, then when they see a good income, they fall into greed and gradually become addicted. This is what happens in most cases but some people have the ability to control their instincts like @perfect999.
The curse of gambling can catch the addicted people easily and there are ongoing live streams, promotions, deposit bonuses, free money offers to bring back the new users to gambling platforms and feed their addiction if they ever fall into this trap once. Promising and promoting big wins and offering huge bonuses with big turnover requirements can trigger addiction so they can keep depositing until bust or reaching the desired level of satisfaction.
Actually, the thing is not just happening like how you explain, it's true that people are getting addicted to gambling very easily but this is totally his/her own responsibility. Casinos don't encourage their users to become addicted, they just offering huge bonuses to bring back their loyal players only. they don't have the intention to make them addicted at all. Those who are addicted to gambling will be addicted by nature/characteristic, they also bet in real life in every case. So, you can't prevent them by giving fewer deposit bonuses or limited free money offer.