Trickle down economics should work this time around.
When has it not?
Almost ever? Certainly not in an environment like this. When marginal rates are confiscatory - like they were in the 50s, 60s and 70s - releasing capital sometimes works. But they were 70-90% then as opposed to 39% now. These cuts are simply a big Keynesian stimulus when we don't need one. Balance/reduce the damn budget/deficit when the economy is growing....like now....and go with the deficit spending when it needs a goose. Which it probably will. Soon. And we'll be out of powder.
As far as how capitalism works, you seem to have no clue. If beneficence of the rich is required for capitalism to work, I guess all the poor countries are fucked, they should just go commie. Capitalism works when free actors create value though ideas and efficiencies. The greatest capitalists in our history - Vanderbilt, Carnegie, Ford, Rockefeller, Gates, Bezos - didn't rely on the patronage of the rich. They went out and generated wealth through their creative brilliance, managerial brilliance, focus and hard work.
I'm not against tax cuts in general, and me and my company will benefit tremendously with the new law, but this is the absolute wrong thing at the wrong time. No tax reform is worth a flying fuck unless it abolishes the abhorrent carried interest loophole, and the fact this one doesn't shows that it is simply a give away rather than a serious piece of legislation. I'll be richer than I otherwise would have next year, but I won't being doing a damn thing for the economy. Probably pocket the proceeds and maybe go on a nicer trip to Europe.