Gambling is a addiction bad addiction. Few days ago I see a user lost 65BTC and another user 30BTC amd another user 12BTC in a dice site. All those user lost huge huge within 24 hours.
But even if we say that it is a bad addiction, a lot of people are still gambling despite the fact that it will really bring you down to the pit. Regret and depression is one of the most popular effect of gambling to people.
Also, these gambler might be rich so they have nothing to worry about those losses. We don't know what they are thinking losing that great amount to the site but all we know is that they had lost and it is hard to get that back.