Birthday Presents

So recently a bunch of my school friends (we are in a chat group together) decided to celebrate each person's 40th Birthday by putting money together to buy a big gift for each person – they are all dotted around the world so it was a collection to post something to each person sort of thing. I decided not to put money in because I find it strange that people celebrate the day they happened to be born, and also, I like to buy gifts myself rather than do some shared thing if I do ever buy a present.

Long story short, one of my friends got really annoyed and has stopped responding to me. I've asked him why but he doesn't respond anymore. I realise birthdays are important to NT people but am I the only person who thinks it strange to buy someone something for a day they happened to be born on? ...and what should I do to remedy this situation now?