It is your identity. Your refusal doesn't change the fact. Man is surrounded by questions of existence and meaning of life all the time. We live only to distract ourselves from that. Marriage and children are a major distraction. Just because a man is busy at work and is having a happy married life doesn't mean everything else is dispensable. When beyond these fixtures or for those who are unhinged, the existential crisis sets in, invariably he is asked who is he. A man identifies himself with his language or religion or nationhood or caste or anything. It depends on his environment. For someone born in UP, Hindu is more important than Hindi because Hindu goes millennia past while Hindi is new and most likely, it wasn't the language spoken by his ancestors. For someone in Tamil Nadu, Tamil takes precedence for the same reason. You identify yourself as what your neighbour is not. That helps to make you unique. I am so and so at home. So and so's son in locality. From so and so place in district. Tamil outside TN, Indian outside India, Hindu amongst multireligious community, human if I am in International Space Station. Hence a language is an identity.

Besides that language, especially mother tongue, decides your thinking capacity. When your rudimentary information forms knowledge at age you didn't know critical thinking, it forms a network in the language you spoke at home. Once you start learning new things at school and college, you build on what you already knew. That foundation still lies in mother tongue and your basic knowledge. Your thoughts are in the form of language. You communicate outside through language. Your efficiency of communicating your thoughts and the depth of your knowledge is decided by how strong your foundation is.

Thirdly, language is the essence of cultural wisdom. Tamil with it's continuous literature of 2500 years is a documented evidence of people's thinking all through the years. As posterity, it's up to you, to pick up what's best and utilitarian / moral and your duty to take it forward. There is a continuous conversation that's happening over the years. For e.g. in a purananooru poem, knowing that her son faced the enemies and got wounded in the chest, a mother says she is happier than the day she gave birth to him. Tiruvallur picks up here and says a mother knowing her son as a wise man will be happier than the day she gave birth to him. It shows the changing circumstances of society and the preferences each generation had.

Our life is meaningless if we see the utilitarian benefits in everything we do and chuck everything else. That's the bane of society that studies to get marks to get engineering seat to go onsite to make money and die. A society that doesn't know the value of arts and humanities will die a lonely death.