worse, the term, as these kids are trying to use it, doesn't actually make any sense.

"trickle-up" implies that money is moving from the lower classes to the upper classes. that's what up means, in context: from the bottom to the top. and, that's how people like stiglitz used it going back to the 90s, at least. it doesn't imply that the money is being invested, or being better distributed amongst different people. if you want to use the stream or spring analogy in context, the right idea that you're trying to get across would be something more like an "irrigation economy".

what they've done is just take some language they don't like, and reversed it in a way that makes no actual linguistic sense.

...because the truth is that they're not very intelligent people.