Can someone point out something that the trickle down theory actually worked?

It did what It was supposed to do. “Get Ronald Regan elected president”.

Peeing standing up.

Piss Up a Rope

All you need to do is use its real meaning as opposed to its propaganda meaning.
The latter being that if the top is wealthy, the less fortunate will benefit from it.
The real meaning is that the fatcats at the top are having a fattening feast, while you, the starving mutt scurrying around on the floor, only get the occasional crumbs that unintentionally fall down.
You are in the desert, the sheiks are frolicking in a massive pool full of water, and you, near death from thirst, are relegated to the occasional splash of their dirty bath water.
They are taking a massive shit and piss, and you on the floor below, can only get the water dripping from the leaking toilet.
Once you realise this, you know that “trickly down” works just as intended.

No. It definitely did not.