+1 for Dude. I want that meme.
Alas, Pemberley, tons of sympathy but no great answers. DS has extreme issues with writing, attention and executive function (and is a tad ASD-ish), and passing elementary school has been a massive challenge. Yet I still get constant random comments from my own parents along the lines of "If DS decides he wants to, he'll do great in high school". The absolutely best-est most amazing teacher ever (and himself dyslexic) will still say things like "I know DS can stay focused in math, so he just needs to try harder in writing. He's very immature, he needs to get his act together and grow up".
The constant message that's it's laziness, lack of willpower, and a moral failing is just deadly. But if I can't even get through to his nearest and dearest, I despair at the rest of the world. Sorry, this isn't helping, is it? (sheepish face)
Huge hugs, and sending you back to Aquinas' more helpful response.