is he too old ?

I’m 17 and i’m talking to a 20 year old. I really like him and we’re really good for each other. But recently i’ve been getting a lot of hate from others saying he’s way to old and that we’re in 2 different parts of life and that it’ll never work out.. Is he too old? ps, this isn’t my first rodeo. he’s not the first guy i’ve dated that’s a few years older than me.