A. You are trying to highlight that the poster is technically incorrect, so that they learn a new fact. That is mostly fine, but it doesn't add a lot to the conversation, and distracts from the point that they are trying to make.
or
B. You are making a point that some people succeed despite handicaps, essentially that there are often exceptions and hard work can make up for lack of talent. This is true, but it's a mindset that I think should not be encouraged in the OP. They are clearly having problems with how hard they work, which had lead to them being institutionalized. Telling them that they could have succeeded if they tried harder is not what we should do here.