I’m personally not convinced that long-term investments deserve preferential tax treatment relative to any other form of income. In my 15-20 year career I don’t see what problem they’ve solved.

Where are the sawmills? Where are the semiconductor fabs? Where is the housing inventory?

Why not give preferential tax treatment to workers who stay at jobs for 5 years? (I’m just making something up, but if you have no strong priors here, what’s the argument?)

At a high level what we’re trying to do is:
-fiscal/monetary policy that fosters full employment
-full employment pushes up wages and inflation
-which leads to companies being incentivized to do productivity-enhancing/labor-saving investments
-which leads to higher growth/profits