To be honest I've never been the type to care what people say or think, but sometimes it brings great joy to prove someone wrong. That moment when someone is like "You can't do that." or "You'll never be rich or successful." or "You're not that smart and that requires someone with brains (which all of us do have)" or "You'll fail, don't try it."... Literally that moment when you like, Just because you said that I will prove you wrong and succeed! We all have at some point proven someone wrong, our teachers, lecturers, parents, friends, coaches and sometimes even proven ourselves wrong.
You have to stop believing you can't and just do it, just prove them wrong. It's an amazing feeling, for real, not only because you achieved whatever they said you couldn't ACHIEVE but also to just say "I DID IT, i SUCCEEDED!!!"