This proverb just means a person who is of a certain age should know better.
I told someone who is about twenty years younger than me that I liked her, and unsurprisingly she ignored me.
The proverb came to mind, “there’s no fool like an old fool“.
There’s also another saying though, which means “you should try” which is (in my local dialect): “Shy bairns get nowt”.
Which means “shy children get nothing”.
The American version is: “It’s the hinge that creaks that gets the grease”.
“Nice guys come last”.