Exactly how does consumer spending increase if it's just redistribution? And assuming it does, why is that good? What about consumer savings being reduced due to less net income for the earners?

I'm having trouble seeing how this could work. If gross income generated, not redistributed, doesn't change (this doesn't create more work completed, it just moves income to someone else). then how is new wealth generated? It seems like spending would likely be the same, if not be reduced due to friction and overhead which would reduce net income across the board (wealth redistribution isn't free, so if new wealth isn't generated, then net income seems like it must go down, and aggregate spending would also go down).

I can't see any plausible way that these numbers will even approach the ballpark of $5 trillion. Back of the envelope calculation please.