While I am probably rather extreme in my birthday-hatred, I certainly know other people who are birthday-phobic in real life. The thing is, that if you don't know people extremely well, you probably won't know that they are birthday-phobic, because they won't make it known when their birthday is.
I think there are a certain number of people on MN who are judgemental of others who don't 'do' their birthdays in the same way as themselves, and this happens in both directions. I have certainly come across the 'childish and entitled' comments; but I've also come across posts where people who dislike their birthdays are accused of being 'miserable curmudgeons', anti-social, ungrateful, or insincere; and where dislike of ageing is seen as simply vanity.