How often do your best friends/friends in high school stay your best friends/friends later in life?

Well I’m currently in high school right now and I only really have one best friend and only a couple people I really consider my friends. How many of them are going to actually still be my friends later in life? I’ve heard people talk about how most of their friends in high school they never saw again. Is this true? Am i going to never see some of these people ever again?