Tami,
There were many profesional gamblers on board (most travelling under assumed names). In fact, The 1st Class Passenger List had a small insert in the front that warned:
SPECIAL NOTICE
The attention of the Managers has been called to
the fact that certain persons, believed to be Pro-
fesional Gamblers, are in the habit of traveling to
and fro in Atlantic Steamships.
In bringing this to the knowledge of Travelers, the
Managers, while not wishing in the slightest de-
gree to interfere with the freedom of action of Pa-
trons of the White Star Line, desire to invite their
assistance in dicouraging Games of Chance, as
being likely to afford these individuals special op-
portunities for taking unfair advantage of others.
All gambling was in the form of card games, usually played in the Smoking Room.
Hope this helps,
David.