“fund this plan through tax increases on ‘high-income Americans’”
High-income Americans in many places are called dentists and medical doctors. They will stop accepting new patients and Uncle Sam will after a few years have to cut deals with the ADA and AMA on special income tax cutouts for medical licensed professionals.
What will happen is the government's definition of "high-income Americans" will be lowered and lowered until it hits teachers, nurses cops, firefighters, first responders and others in that tier, all the way down to Walmart and fast food workers - until anyone with a job will be considered "high income Americans."