So schools are using games to educate kids. Minecraft edu has been used by numerous schools and other math games has taken over math classes. What do you think about video games on education? Will they increase video game addicts or not?

Using Minecraft can induce addictive behavior further down the line. 

As for other gamified platforms, it depends on what kind of mechanics are introduced. Duolingo is bare basics and having the streak mechanic is actually good for making sure people come back to practice. 

As far as I am concerned, if the mechanics used in the gamified platforms are similar to those used in MMORPGs and mobile games, then yes it will increase addiction and open the door to the very games that cause said addiction. Otherwise, if it is bare basics mechanics that encourages regular practice and learning, then it will not produce the kind of addiction that stems from other types of games that are deliberately designed for keeping people addicted.