As well, my feelings towards my own birthday are entirely indifferent. Even since early childhood, they were never approached as something of importance. The anniversary of another 365 days since my birth has no impact on me, although the gravity of aging is hard to avoid.
Expectations and comparisons to others more successful is something I am guilty of, but I do not specify age within my jealous thoughts—more so, I just want to feel the happiness they feel and appreciate life for what it meant to be. If I knew what the future held, I may be able to tolerate more of the mundane events that occur in my life, than wishing I could be more like the people who seem happier than me.
When people vision birthdays, they see streamers, banners, cake, party hats, and our creepy uncle Chester who is giving everyone weird vibes and wishing they hadn't invited him. It's such a grand vision that naturally brings us all joy and when we see ourselves alone, eating microwavable foods on what was meant to be such a joyous day, we are compelled to develop the notion that we dislike birthdays. It just brings back that feeling of disappointment and forces us to face what we want but do not have.