What do you think?

منذ ٥ أعوام

A few days ago I had a discussion with one of my friends about teaching foreign languages, and his opinion was that it's not necessary to take lessons with a professional teacher if you want to study a foreign lenguage. "Because if you are smart enough, you can do it by yourself without any help. And learning a foreign language is not like learning a nuclear science, for example, to learn a foreign language is so easy like to eat a honey." 
What do you think about this? Have you ever faced with such an opinion in your countries or it's just Russian mentality? :)