In Egypt, the illiteracy is worse than in Turkey, so I think the education level isnt the only cause 
He ascended to power with the votes of liberalists who only cared about large-scale privatization of state assets and leftists who believed he would actually bring the general responsible for the coup d'etat of 1980 to justice (he, himself, is actually a byproduct of that coup and it was obvious even then -2010- that the justice part was never going to happen).
At this time however, failure after failure, the illiterate are the only people who still support him.
Late-coming edit: His recent bans on social media should give you a clue. His current supporters are either not good at social media or don't use it all, save for his well-paid web trolls (wiretapped calls are available to document the presence of even those trolls, yeah, fucked up I know). So these bans are all meant to be his display of power in their eyes.
