You get birthday parties? I didn't, stop complaining.
I'm going into technical mode
er hurrm *clears throat*
Everyone has a right to complain about something that changes in our life, as most human beings do not value change. OP has always had birthday parties, so when something interferes with tradition, he's allowed to let out his emotion about it.
Just because you didn't doesn't mean he has to stop complaining and you're dumb for thinking that.
Let me throw in another example to make this more clear.
A rich person is very (OBVIOUSLY) wealthy but one day goes bankrupt.
a poor guy tells him that he has no right to complain because there are others who barely make it through the day, however, that's all the rich person has ever known, so when something changes for the worse, he's obviously going to complain.
The poor person was never rich, so he is in no position to say such an absurd thing. While it seems unfair, that's life and you should get over it.