Language courses can be expensive, especially when taken at a language school or college. Not only do you have to pay for tuition, but you also have to pay for books and sometimes also for expensive learning aids such as CDs or DVDs. Cheaper options exist, such as online courses or foreign language books, but they can be less entertaining and efficient than learning with others in a traditional classroom setting.
Learning a language takes several months, or sometimes even several years, of weekly courses. Not only do you have to attend classes, but you also have to travel to and from the school, making learning a language an important time investment, time which you could otherwise spend on your family, hobbies or work.
Foreign languages can be difficult to learn. You have to learn a completely new vocabulary and master the grammar and the pronunciation. Languages like French or German, for example, have much more complex grammar rules than English grammar, making them both difficult to learn, especially to people who have been out of school for quite some time.
Foreign languages are not always useful, especially to native English speakers. You can travel or conduct business everywhere in the world in English since it has become the de facto language of international communication. Before taking on a language course, ask yourself whether the time you will spend learning that foreign language would be better spent on learning a more useful skill, such as computer skills or math.