“The big question is whether or not it ends up in enough of the right pockets, i.e those of people who will spend it, or in too many wealthy pockets, because wealthy people don't spend like the less well off do.”
That is the problem wealthy people don’t spend the money they invest it, it starts at a very low level with house buying, that cash is removed from the economy. It has supported the company that built it and his workers, after that most of it attracts very little tax.
The wealthy invest in shares, pension or business growth, not consumer spending, they also “live” the business, most of their social activities are connected to the business.
The Ultra wealthy with international businesses can direct the cash to where ever they want to, houses, yachts, areoplanes and cars are owned by the company.
Taxing the rich is very difficult.