Agreed. Investment is the machine that moves the economy. Consumption is the natural by-product of people investing in their power to produce more value. When you produce value in the world, the world pays you for it and you are able to by what you want (miracle of exchange and currency).

I think you may have been down-voted because you forgot to mention that the investment you refer to is not investing in a 401k or S&P 500 fund. You refer to business spending on capital goods, new technology, entrepreneurship, and productivity. Retail demand grows with wealth. The worry shouldn't be on a future where we don't demand, as demand will always find new products to make scarce. We should rather worry that wealth will be redefined as having things, which will reduce a person's focus from producing to consuming. If we are all worried about consuming more and focus our effort and energy there, we'll stop focusing on producing and will then turn to financing our consumer goods (spending tomorrow's capital today).