I just had a life milestone last month. I finished 2 years on the job. My first 2 years working hard (and making money for it!) out of school. And it ended in an 'on time' promotion. Ye to that!
I like milestones. Like, I always make a big deal about birthdays. A big big deal. There has to be cake; and phone calls at 12 mid night, a plan for the day, not too much time spent in bed on the day, a visit to the temple, dinner with your best pals, happy flowers from distant friends, etc. etc.
I like the idea of a big new year's celebration. Or diwali. Or Christmas. I know a lot of my friends don't. Especially, new year's eve. What's the big deal? It's just another day. I agree. the 31st of December is probably one of many more to come. But what I love about new year's eve, is whether you like it or not, at some point during the day, a kaleidoscope of the year will run before your eyes. I love remembering crazy moments during the year, silly fights, sillier impulsive actions. I love all of that. So yes, the fuss is not about 31/12/xx so much. It's about 1 day every 365 days or 500 or 737 - I don't really care; when you sit down and think about all that happened since the previous such time - in a flash. I love the feeling that washes off you as you live that moment. That kaleidoscope.
Funnily, it always seems so happy.