Gambling in islam is forbidden.
"O ye who believe! Intoxicants and gambling, (dedication of) stones, and (divination by) arrows, are an abomination,- of Satan’s handwork: eschew such (abomination), that ye may prosper.
Satan’s plan is (but) to excite enmity and hatred between you, with intoxicants and gambling, and hinder you from the remembrance of God, and from prayer: will ye not then abstain?
Koran 5:90-91
It is considered the work of satan.
Now, whether they abide by this is another story.