If what is being discussed is living in an English speaking nation like the UK or the United States, then of course English is necessary. Other than that, of course people need to be fluent in reading and writing their own language first. Then English would be a very beneficial second language for anyone to have.
Most of us know that now English is considered as the most speaking language in the world.
This greatly increases the importance of the language.
Languages are basically just used for communications.
But, What if the majority of the world speaks a certain language, perhaps like English?
Then if one knows English you could say that he/she is most likely able to communicate with a huge amount of crowd.
Therefore, This gives a huge importance to the English language which makes it necessary in life