Define “High Earners”.................
Anyone not on welfare.
In this context it's probably referring to people who make too high of income to contribute to Roth IRA's ($153K for filing single, $228K for married -- as per https://investor.vanguard.com/investor-resources-education/iras/roth-ira-income-limits#modal-magi). Roth 401K's (and Roth 403B's and Roth 457's) have no income limits.