Plural adjective

Question

Quiz question: "Cuanto más ricos, más desgraciados.The richer [you are], the more miserable [you'll be]." Why are these adjectives plural? (They are adjectives, right?)

Accepted Answer

Hola R
This is using the adjectives in plural to refer to a you plural as in the general public, referring to people in general. But you could also use this in singular:
"Cuanto más rico más desgraciado"
However, if someone says this in singular the listener would probably think the speaker is referring to someone specifically and would ask "who are you talking about?"
The expression in plural makes it clear that it is in general.
Saludos
Inma