Revenues have averaged 18.1% of GDP for forty years, regardless of marginal tax rates.
Two things can cause debt to skyrocket, and both at the same time can cause it to double-skyrocket.
1) If CBO revenue projections---that we'll by able to boost revenue-as-%-of-GDP to significantly above historical average for an extended period of time---fail to happen, debt will explode.
2) If CBO outlay projections---that we'll be able to significantly reduce expenditures (even though there's no legitimate plan to do so)---fail to happen, debt will explode.
If both CBO projections don't really come true (we don't sufficiently decrease spending and we don't sufficiently raise revenues as percent of GDP), we're completely ****ed.
Raising tax rates does not guarantee much greater revenue as percent of GDP, because it's a dynamic system. Revenues jumped when Clinton was in office concurrently with tax rate CUTS to capital gains. So WTF? Tax rate cuts and hikes affect revenue, certainly, but in dynamic and not always predictable ways. Tax cuts can stimulate economic activity resulting in greater revenues, in some cases, and tax rate hikes can deter economic activity and lead to dwindling revenues, in some cases. Dynamic. We've had varying tax rates for a long time and not necessarily had meaningfully higher revenue as a percent of our GDP.
Meaningfully increasing our revenues depends most heavily on our ability to experience another economic boom. Deficit spending does not create economic booms we need to recover our deficit spending -- that is a losing game.