You know what else you didn't earn? God's love. Stop being a jackass.
Excuse the harsh language, but the people who go on about that deserve the title. Everyone has at least one friend who enjoys making you feel terrible for liking yourself. They are not being a particularly good friend in that moment. Ever notice how we tell everyone to believe that they are beautiful but the second someone says they are beautiful out loud everyone considers them to be narcissistic? Quite the double-edged sword.
It is okay to celebrate yourself. You are worth it. No, you didn't have to earn it. You are an incredible creation of God in God's image, fearfully and wonderfully made. In fact,
For it was you who formed my inward parts;
you knit me together in my mother's womb.
I praise you, for I am fearfully and wonderfully made.
Wonderful are your words; that I know very well.
My frame was not hidden from you,
when I was being made in secret,
intricately woven in the depths of the earth.
Your eyes beheld my unformed substance.
In your book were written all the days that were formed for me,
when none of them as yet existed.
Psalm 139:13-16
You have a birthday because God and your parents co-created and wanted you to be born. That is worth celebrating. God wants you on this earth, so God created you. It is more than okay to recognize that you are a gift to this world; that is how everyone should see themselves. You are a gift God gave to the world. That is something to recognize and to celebrate.
Some people like to say that respect has to be earned. To me, that is horrifying. A person should be respected because they are fearfully and wonderfully made in the image of God. Any person you meet is also created by God and also God's gift to the world and should be treated as such. They have dignity as a loved creation of God and they deserve respect.
Which brings me to the first and most basic of the seven themes of Catholic Social Teaching: the Dignity of the Human Person.
"We believe that every person is precious, that people are more important than things, and that the measure of every institution is whether it threatens or enhances the life and dignity of the human person." - USCCB "Life and Dignity of the Human Person"
"Human persons are willed by God; they are imprinted with God's image. Their dignity does not come from the work they do, but from the persons they are." - Centesimus Annus
A birthday is a celebration of the person you are, not the work you do. Other people get to tell you they are glad you are. You get to say you are glad you are, and you are happy you have people who want to celebrate with you. Giving thanks to God for creating you is worthy of a party.
Of course, there is the birthday party with an agenda, to show off money and take a vacation from virtue. That is not a celebration that thanks God for creating you and honors your dignity, but a party that tries to prove your earthly importance, influence, and affluence. That is the party our misanthropic friend at the beginning of the post has a basis to criticize.
If, however, you just want to go to your favorite restaurant with your friends or your brother wants to bake you a cake, there is no shame in enjoying yourself. I am here to say that your party pooper needs to re-think their commitment to social justice.