Yes, educating all people will generate a bigger advantage in total. What I meant was that an individual will obviously make more money for themselves if they h

Yes, educating all people will generate a bigger advantage in total. What I meant was that an individual will obviously make more money for themselves if they have free labor that they can exploit. So a society of N educated people will make less money than one of N people + S enslaved people, but a society of N + S educated people would make even more.