Trickle-down economics is a term of abuse

Nobody (or almost nobody) promotes anything they call trickle-down

What it actually refers to is the idea that tax cuts might spur growth, which they can do. The term is most associated with Reagan's tax cuts, but JFK before and Obama afterwards had similar tax cuts. In Reagan's case tax revenues increased after the tax cut - because they worked and did actually spur growth. I'm not familiar with the others but I believe they also worked.

What actually impoverishes people are excessive taxes, grants of monopoly privilege, regulations and (in the absence of regulation) failure to enforce common law.