Sentence:  This book is primarily for alpha males, or “top dogs.” We'll talk more about that later; but let's just say that if you are a man and successful in the world of trade, business, or profession, most likely you are an <WSD>alpha</WSD>, or you have been trained to "act like" an <WSD>alpha</WSD>. 
Meaning of the word marked with <WSD> tags:  A person, especially a male, who is dominant, successful and attractive; (see alpha male).