Assalamu Alaykum wa Rahmatullahi wa Barakatuh

I'm a student and I go to a college where every year they celebrate the eid milad-un-nabi.As my parent consider this as bida'a,I do not go to school on that day.Normally,they request every student to give a hand.Mawlana Anas (from Pakistan) used to come there,they use to sing naat loudly ,they stand to perform the salaat-u-salaam (sending Durrod to the prophet)and there after meal is distributed.Teachers and student and my friends who celebrate the eid milaad-un-nabi used to ask me questions why I do not celebrate this day and I have no answer for them.They used to ask me also to show them proof from Hadith where it has been mentionned that to celebrate this day is not permitted ''Bidaa".what I would like to know is why some people do not celebrate the eid milaad-un-nabi? I would prefer having answers with the proof of Ahadith.

Wassalam
Soumaiya