The main reason why the author uses words such as "dangerous," "suicidal" and "uncontrolled" is because he is trying to appeal to the reader's emotions. In these lines, the author talks about the consequences of being too generous with resources, and he highlights the important and risky consequences this could have. In order to increase the persuasiveness of the argument, the author uses intense emotional words.
According to this paragraph, I would say that the tone is sad and informal. It could be considered sad because of her personal experience. How she also felt when her first boyfriend left her for another girl.
