Sorry, But Not Happening In This System
Restrictions on earnings would require politicians, whose careers depend on money from the wealthy, to bite the had that feeds them. Never happened in history. As for limiting earnings as income (vs. capital asset appreciation), this will soon be a thing of the past as almost all jobs go to machines (see my article, Capitalism and Post-Capitalism — The Whole Truth & Nothing But)
As for campaign reform, Supreme Court decisions, first Buckley v Valeo and then Citizens United killed any consequential campaign reform. Suggest you might want to read my article, A New Process to Fix Our Political System.
Doc Huston