If I can speak for the word "retard" - in reality it means "delayed" (i.e. fire/flame retardants) which I know comes from the French language verb "Retarder" (delay)(I never dug further to see if it has a latin origin when I was learning French).

On the example it's the typical - the "the early bird catches the worm".. meaning the first to get in the trade, makes the buck, the last one in is stuck with an overpriced stock/instrument which is about to deflate. So.. they got in too late.

The "retard" that (unwise & unkind) people use comes from "developmental retardation" (https://healthquery.net/developmental-retardation.html). And the rest is history...

This results in the apparent plane insulting the pilots: https://youtu.be/vmbzKsqKQoI

But it’s just telling them they can flare.