I don't think I've ever celebrated my birthday. But when you never did something, you don't really miss it. And since my mom was (and still is) a 100% diehard, the only people we were around was other JWs. So I didn't even see other kids have birthday parties. When you don't know that you are missing something, you never miss it.
But yeah, stuff like Halloween, Thanksgiving, Christmas, those are a lot of fun now. I never went trick-or-treating and I am fine with that. I did enjoy getting to give kids candy once or twice, and my only regret about my house is that it's in an area where kids don't come by to trick or treat. The other holidays are really about getting together and having a big family/friends meal, and that is always a treat no matter the occasion.
And I enjoy getting gifts for close friends and receiving whatever oddity or knicknack they get for me. You can keep your once-a-year, watch-someone-else-partake "night of observance" or whatever it is. I'll enjoy myself, instead.