Yes, limit the amount played in the casino to overcome not going bankrupt, because there have been many cases where they did not control the budget for gambling and ended up losing everything.
Just 5% of the total income is more than enough because the purpose of playing in the casino is only for fun not profit.
But somehow until now there are still many people hoping to win a big jackpot from a small budget.
5% is a decent safety margin in order to not lose control over financial expenses with gambling. Some gamblers still go beyond and adopt a 10% from total income strategy, but they must keep in mind to be actually sacrificing money they could be spending with other leisure activities, potentially side by side with their families.
It's a personal decision each one has to make, and nobody else has anything to do with this, but it never hurts to give benefical and worthy advices to people who we encounter in life, so we can try helping them somehow, especially in this case where we can advise them to risk less money from their total income with gambling.