Why do friends let me down on my birthday?

Whenever I plan an event or do something for my birthday, friends always let me down and never show up. I know I shouldn’t be complaining on here but I just need to rant, as it upsets me how I make an effort for everyone else on their birthday, but when it comes to mine everyone shrugs it off. It hurts and it shows to me no one actually cares about me as much as I care about others, and it’s really effecting my mental health. Why do I care about others more then they care about me?
Why do friends let me down on my birthday?
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