Why do people care less about your birthday when you get older to adulthood?

Last month I got told this, “The blunt truth is, nobody cares about your birthday. They have their own problems and they’re not obligated to wish you a happy birthday. Get used to it and get your ass out of the fantasy world.”
Rude and I was told that when I turned 19.
I was sick on my 20th birthday. Not a lot of people wishes me a happy birthday but some people did stop by and wished me a happy birthday. My birthday was October 15th.