But many is so lazy to put a security measure to avoid those hacking issue on their account and they will always threath the 2FA as a hassle option to put in their accounts that's why it's not surprising to see man got fall from hackings. And your right we should follow the recommendation since the casino knows it is best for any to make their account more safety.
That is because they don't think much about security for their account, whether their account in the gambling website or on the other website, and once their account gets hacked, they feel regret. They try to ask other people how they can get their account back, even get their money back. But everything already happened, and they can't do anything to have their money back. The casino wants to protect their member's accounts, but if their members seem don't care about their account, that is their member's decision.