It's tough when it feels like you're the casino's personal punching bag. That kind of a loss, particularly over a short duration, feels like a blow to the gut and can literally take your breath away - I'm speaking from experience of course!
I have worked on various psychological countermeasures to the discouragement and anxiety that can ensue in these cases, and while I still struggle with it, I have found that such measures can be of assistance. For me, the military analogy is useful: You are like a soldier under intense artillery barrage; in this situation, the green recruit can easily break and rout, but it is the soldier's duty to endure and continue to fire his weapon; and the crack, veteran troops are able to carry out this duty without question or hesitation. Even they feel fear, but that fear is held in check by their superior training, experience, and mental toughness - as well as their overriding sense of duty and diligence. It is our duty to take it to the casino and punish them for offering games that can be beaten, and it's as simple as that.