As a global citizen living in a diverse nation, following a unique religion, I am required to deal with many different types of calendars. This has lead to me having at least three New Years.
As a Muslim, I follow the Hijri Calendar. It is a lunar calendar and it has the first month of Muharram. All events and festivals of Islam are tied to this calendar. Like Eid-ul-Fitr, which is the first day of the month Shawwal, is celebrated after completing the whole month of fasting, that is compulsory for every physically and mentally fit Muslim, in the month of Ramadhan. Another Eid is the Eid-ul-Adha, the festival of sacrifice celebrated during the month of Dhul-Hijjah.
As a global citizen and a professional, I follow the Gregorian Calendar, about which I don't have to talk. It is the standard January to December calendar.
As a Telugu Bidda (child), I have a Telugu calendar which is also a Lunar Calendar and has its own months. Ugadi (ఉగాది) is the New Year for this Calendar. The calendar is called a Panchangam (పంచాంగం).
I wonder if I need all these calendars sometimes. But each and every community has its reasons to retain its calendars, it becomes the responsibility of an individual to determine what he wants to follow and what he can skip.