Let's break down your question one at a time.
Oxygen is not flammable, it's an accelerant. You would have to be pumping dangerous amounts of oxygen to the person's health to increase the fire risk and it would have to be produced offsite and transported in liquid form to even approach the amounts needed for this, you'd see a very large white tank fenced off, that was getting filled every day or two. Check behind hospitals to see what I mean. They use a lot of oxygen and it is very expensive in heavy usage. Also the alcohol usage of people in the casino would lower the effectiveness of the extra oxygen.
The typical outpatient I serviced as an Oxygen Delivery Tech received a dose of 2 liters per minute. A patient who was in excruciating pain and in the process of dying would receive up to 10lpm for short periods of time. An oxygen concentrator that people typically use instead of liquid oxygen pulls oxygen from the surrounding air and only improves the patients airflow roughly 6 lpm by being directly injected into the nose through a cannula or mask, in some cases through a bipap or cpap machine, especially in the cases of sleep apnea.
Too much oxygen can actually be detrimental to your health and cause euphoric like effects, along with other affects similar to oxygen deprivation. While liquid oxygen is stored cryogenically the only affect that would cause you to wake up is the affect of being surrounded by the cold. Oxygen dries you out and if you don't need it and take too much can harm you. There is no way that this is happening. Cost wise it's also cheaper to get people drunk than to give them oxygen.
From personal observation, the smoking areas in many nursing homes and hospitals I service happened to be right next to where the oxygen tanks were stored or filled. The process for refilling certain portable tanks requires that you vent the pure oxygen gas while you put the liquid oxygen into the tanks. I would have these vents pointed away from the smokers, yet without fail they would walk right into the oxygen vent stream with no deleterious affects. We even had a patient who would use his oxygen tank as an ashtray.
@Brian Knoblauch - typically we charged about a dollar a pound for liquid oxygen, if I remember correctly, it's definitely not cheaper than alcohol.