All kids tend not to be observant wrt other people's reactions. The ability to communicate with a broad audience at a young age is itself a sign of intelligence.

My point is that OP was treating the "big words" dismissal merely as a signifier of intelligence. It's also a signifier that one lacks the ability to communicate clearly with others. That's hardly a revelation wrt 4th graders, but it's worthy of reflection at whatever age the OP happens to be now. I know plenty of people who enjoy wearing that inability as a fashion just as people now buy designer "nerd glasses."