Why do they celebrate on New Year's day?

I've never understood why people celebrate New year's day. There was a time when hotels and restaurants were full on New Year's eve, but after the Jamat-e-Islami threatened to disrupt the festivities, there are no parties on that night. I've heard that private parties are still held. At that time, I could understand why the religious party had to prevent people having fun (the reason they gave was that it was not a Muslim festival, and it was not proper to indulge in such activities due to the rampant hunger in the country). 

But the core question is, why do people celebrate on the first of January every year? Even though I had my primary education in a missionary school and saw the Roman Catholics going to church on this day, I still doubted if it was a religious requirement. Now I know. It seems that Jesus (being born Jewish) had been circumcised a week after his supposed day of birth), and it was the custom of the Jews to pray and celebrate on that day (I remember, when I was young, Muslims also observed this practice). So the followers of Jesus did the same thing (remember, for four hundred years, Christians considered themselves a Jewish sect). 

So, despite the fact that Jesus was circumcised, Christians are not, they are baptized. Why this is so is something that needs to be investigated. But again, why do Pakistani Muslims come out of their houses on New Year's Eve, firing their guns in the air and exploding fire crackers? They bullets falling to the ground kill and injure many people. The noise is so deafening that I'm not able to sleep. Moreover, despite all that poverty, Pakistanis prefer to waste petrol driving to the beach to indulge in mayhem. Both petrol and the chemicals for making fire crackers are imported (using precious foreign exchange). At least for this reason alone, the government should ban celebrations on New Year's Eve.