NBA players are just people at the end of the day. Despite being athletically gifted and incredibly dedicated people, they still are subject to the same rules of life just like us.
When I was a kid, I was always the smallest around. My dad was six feet tall, and I would lament the fact I never would be six feet tall myself. I got made fun of for being slow to grow. I remember a kid looking in my sleeve in seventh grade and laughing at myself for not having armpit hair.
I tried out for about 20 travel baseball teams before eighth grade and made zero.