That's not a zero sum game, the spending and the Taxes.
Taxes are a percentage of how much the economy does. If you expand the economy you can have more tax revenue even with a lower tax rate.
Tax cuts have a very limited stimulative potential in conditions nothing like what we have right now. Specifically, when there is a short-term, systemic liquidity crisis, some sort of tax cut can inject cash into the economy to get things moving again. Apart from that, many of the things that business can do that actually results in economic activity are at least partially deductible. The tax system is mostly designed to tax the profits, so cutting taxes has the impact mostly of making investments more profitable without really creating any avenue of growth.
The reason I say that they will have virtually nil impact right now is that there isn't a shortage of investment capital. If anything, there's a shortage of investment opportunity, and tax cuts don't do a thing to address that limitation directly. But saying that, there's actually been some good growth in the last year or two, so I list that only as a relative problem. I think the more fundamental problem is that innovation in our economy has left some members of our society behind. Short of just giving them money, I don't know what the solution to that problem is.
Worse yet, Trump's announced tax plan is almost entirely going to the richest people. If you make about $100,000, you get about 1% tax cut. And the lowest wage earners will actually see a tax hike if enacted as stated so far. So, it's almost a pure transfer of tax burden from the poor to the rich. So, it really is "trickle-down on steroids", enhancing rather than ameliorating the structural problems with our economy, giving money from the already poor to the already rich.
This experiment has actually been tried by Republicans repeatedly. Can you point to a case where tax cuts have lead to increased revenue?
What's your biggest fear about The Donald?
So many. I think the biggest is that he's going to turn the government into a kleptocratic client state of Russia with actually rigged elections, like Ukraine under Yanukoych. Also high on my list, the potential for a new nuclear arms race and possible nuclear exchange, given that Putin and Trump seem to have little respect for the lives of civilians, the possibility of defaulting on the debt as he proposed, which would probably instantly explode the deficit and could lead to a catastrophic collapse of the dollar, the chance he could abandon our NATO allies to Russian invasion. The chance of some sort of Hitlarian purge of political opponents and immigrants.