We're running out of fiscal space

The era of easy borrowing is close to an end.  Washington Post editorial board: "When America’s pot of debt will overflow."

This can't be cured by just "taxing the rich":

Budget reforms must be based primarily on spending constraints, not tax hikes. While some moderate tax increases could help reduce the deficit, it is not feasible to structure a tax system in which revenue grows faster than the economy every year, which is what would be necessary given current spending projections.

Even boosting revenue as a share of GDP to the highest levels in American history would close less than half of this year’s deficit, and such a large tax hike would destroy economic growth. No major tax proposal on its own, except perhaps a national value-added tax, comes anywhere near closing the deficit when the effect on economic growth is properly accounted for.

Where are we going to cut spending?

Constraining spending will need to be primarily focused on entitlement programs.

Yeah, good luck with that.