This is the problem when talking about class warfare. We are eating our own. Someone making $300k a year is closer to the median than someone making $5 million a year. Losing ~30% of your spending power since 2008 might not matter if you're a billionaire but for most working professionals it has an impact.
You make a good point - lumping people who make 500k a year with those making 5 million (or 50 million) a year is bad policy.
It's still a very good income, though.