Your entire post is misleading.
It contains the ASSUMPTION that the favorable capital tax rate (vs labor tax rate) is NECESSARY for the investment to happen.
This is obviously not the case. People with capital will want to deploy it so that it grows, as long as the tax rate on the profits is <100%.
What we do not have is the curve - how high can the tax rate be set relative to the tax on labor income before investment is ACTUALLY discouraged?
Only an assumption, based on the obviously self-serving assertions of people who own capital, that higher tax rates will make them just sit on their money and not deploy it profitably.
As you can see above, I'm happy to debunk oversimplification & demonization from the LW or RW, but "trickly down" is pretty much what the RW called it when it was flogged as a concept in the '80s, that "freeing up capital" for the rich would trickle down to everyone in the economy. The ACTUAL result was the opposite. Ratios of executive vs worker pay only increased from ~70x to over 300x, and the share of the total GDP going to labor declined to the lowest point ever.
The actual fact of the matter is that with lowering tax rates on capital, the "boon" you speak of is actually available to fewer people than ever.
