I literally know hundreds of recent Brown graduates and haven’t heard one suggest it was a “lousy expensive fit”. The vast majority are doing extremely well career wise and had great and rewarding college experiences. Those that had financial need took advantage of Brown’s generosity.
Have you ever spent time at Brown? What are you basing your “chances are” statement upon?
OP you are a strong candidate. I would seek the advice of your parents, GCs and people who have first hand experience with the schools you are considering.
It would appear you know more about Brown than many of those informing you about Brown.