answer:Just my two cents, I think it’s some sort of grammatical misunderstanding Quite possible on such a site like Facebook. From my knowledge, the adjective can sometimes be used as a plural noun, things like the dead, the unfortunate… and they alone have the plural meaning. In your case, that person probably wanted to use “better” as a noun, but thought that “because I’m talking about many people, may as well add the “s” like other nouns”. The result was what you saw. It’s as annoying as when you say “the deads” or “the unfortunates”. That person meant to say “the better”, just with an “s” to emphasize the plural meaning.