In a non-dyslexic brain:
The Cerebrum is like a library that stores all your words. It's like perfectly organised all books on alphabetic order, which makes your mind recognize words at lightning speed!
Now you have to think that this library in a dyslexic brain has burned down, only one little part is there and it is a mess, it takes a dyslectic reader three times the energy a non-dyslectic takes to find these same words.
Knowing that dyslexics use different portions of their brains to read is interesting, but it doesn’t explain why these sections of the brain used for reading are less efficient in dyslexic people.
The truth is that there is still a lot that is not known about dyslexia, like why the brain only uses the front part, what causes it, why a dyslextic people have one area of their left hemisphere larger than the same area on the right side of their brain, and what that is used for.
That bigger hemisphere makes the brain physically bigger.
So there is clearly enough evidence that dyslexia actually exists, but it is still not recognized everywhere. Certain people still don’t believe it exists they say: it's just an excuse, and it is sometimes even seen as a curse.