I'm not sure that's true.
The reason is underemployment. when technology disrupts the jobs of educated people, they have options to find jobs that require lower education , or take a job with lower salary , because of their prestige, education and experience.
People with less skills usually have much less options , so instead of becoming underemployed , they become unemployed.
As an example , see the table at .
there are two definition for underemployed. the official is a people with part time job looking for full time job. the other is a person looking for a job below his skills.