There are two answers to the question.
I am not superstitious about anything and have not been since a child - or so I tell myself. Most would say they are not.
However, that does not stop many very successful people, sportsmen for instance, from accomplishing tasks based on a lot of routine behaviors, habitual physical ticks. Rafael Nadal is perhaps most famous for going through the same physical motions before playing each point - wiping his brow, touching his nose then sweeping his fingers over both ears, In fact tennis players are known for imitating each others routines for fun.
But then think of golfers who have precisely the same set up before swinging or putting. Football players have specific routines to get dressed etc etc.
Now, you could say this is a broad definition of being superstitious but the mental state is similar if not the same. The mind enacts a series of habitual actions to get to a point of calm to execute an action. But we act like this throughout our lives in different ways. We create good habits to succeed, instigate patterns of behavior to achieve desired results.
So though being superstitious in an obvious manner appears silly, such as thinking Friday 13th brings bad luck (though most classic superstitions have historical origins) most of us tend to follow odd little behavioral patterns in our life.
And...I would bet the neighbors house that most poker players have a routine before they sit down to play a session to get all their ducks in a row, to relax and focus.