This is an interesting discussion. I could go on and on about the good and bad having been on both sides. You can't know what is going on in another person's mind or how their body reacts to a situation. I can only speak based on my experience. Everyone says they get nervous and just deal with it. Or it will get better over time. That may be true for that person but may not be true for someone else.
I think the most important thing to figure out is what is causing the anxiety and inability to turn off a racing mind when sober. I play great when in non pressure situations sober but when I get nervous, the wheels completely fall off. It feels like a panic attack. Hands won't stop shaking and heart pounding. I feel like I have never played pool before. I notice every external thing.
But with drinks during tournaments or gambling I just play pool. No thinking and calm. Just run out easily and often. 700s arent thrilled about playing me when I am playing well.
I have read books and watched videos on the mental game. Hypnosis, subliminal tapes etc. Some have helped more than others.
Probably the best I have found are a video by Dr Chris Stankovich called Mind of Steel and a book called the Confident Mind. Knowing what to do is only a small part of the battle. Learning how to do it in pressure situations takes serious work.