[luckylion]

> Or tax anything that 10x’s productivity in any field, but at a level where it still is very motivating for an investor to make that 10x investment by letting them keep 8x of the output?

That'd only work on monopolies where the company would actually have a 1000% margin. For most things, you'll invest in some great new automation, but so will your competition. Now you've both increased productivity and if you try to cash in your 10x profits, your competitor will simply take 5x profits, massively undercut your prices and you'll be gone very soon. Productivity gains will typically lead to lower prices, that's why meat, milk etc is dirt cheap these days, if we still had food prices like in the 50ies but with today's productivity, any secret illuminati meetings of the 1% would see a lot more people arriving on tractors ;)