[jaggederest]

If you're considering "investment" as included in GDP, it's not just "saving money", it's "business spending on depreciable assets", essentially. Owning a share of Apple doesn't make you "an investor" in the GDP sense, but Apple does a lot of investment.

I'm not sure that "rich hoarders" have an appreciable positive impact on business investment in depreciable assets. Most capital assets are purchased to produce goods and services to meet demand, which might be stimulated more by redistribution.