If you are old enough to recall Ronald Reagan's insemination of Supply Side economics (trickle down) into the heart of GOP ideology, you shouldn't be at all surprised about what Trump is promulgating as his "tax plan." The tax plan is a mere rehash of past GOP economic policy which almost leads to a total economic collapse.
Two MSNBC news segments best state a case against a return to Trickle-down economics.
I offered two segments, but there is more. If you are an informant geek or a High Information Voter (HIV) MSNBCs Morning Joe Show included an extensive segment with great detail and relevant comment about Trump's "sly of hand" tax cuts.
Now, take a look at the same chart with specific direction to compare two out data points.

If you review a comparison chat of income growth from 1980 through the subprime Bubble burst of the Bush Era, the effects of trickle-down are stark and frankly, "in your face."

If the chart about isn't descriptive enough, check out the is graphic.
Trickle-down (supply side) economics is the most stifling economic measure Republicans had ever administered against the US middle class and lower-income citizens.