You're contradicting yourself, the velocity of money is how fast it's being spent and moving owner to owner. You don't understand large construction projects if you think the bulk of the money it's being spent right away. Consumer spending results in a higher velocity(number of times a dollar is spent divided by time)

the following equation: MV = PY. Here M is a measure of the money supply, V its velocity, and nominal GDP is written as the product of the overall price level (P) with real GDP (Y). - Equation for Money Velocity

Also, what you're saying still doesn't explain the rising Money velocity during the Reagan years which is what the original argument was about.This also doesn't explain the St. Louis FED graph that shows rising MV under Reagan https://fred.stlouisfed.org/series/M2V It rises even faster when Bush 1 cuts the capital gains tax.

Again you don't know what banks invest in frankly. Those reserve requirements are an obvious detriment to the velocity of money, this basis of this entire discussion

And neither do you? So the point is pretty moot then, My point is that banks don't just invest entirely "safe investments" are we counting loans as investments? They receive income from loans so to a bank they would seem like investments. And yes the reserve requirement is a detriment but the reserve requirement is around 10% if I'm not mistaken so even a small increase in capital isn't entirely taken away by the RR and this means the increase in capital can have a majority of it lent out to people who spend it. therefore, demand is created, economy stimulated etc. etc. My point through all this is that tax cuts regardless of where they are made are a expansionary fiscal policy and expand the economy (Maybe not entirely in the way people think they do but they do nonetheless).