So first of all,
DOW is an arbitrary weighted index of just 30 companies. It was created to sell newspapers. Ignore it.
S&P 500 is a better index.
Second, the stock market isn't some meaningless set of numbers. When you buy stock, you own a tiny piece of a company. That money can be used to raise capital to buy equipment, hire people, build careers, create a revenue stream, and hopefully profit. It allows people to contribute to society and create products and services that improve the per capita productivity of society or add aesthetic value to it through arts that can inspire.
The market's price is short term valuation based on many factors.
Long term it grows because it's a reflection of the progression of humanity.
Will humanity continue to innovate and invent? Absolutely. For a long time. Just google all of the applications of Graphene. That stuff will be the plastics and oil of our time, and it's probably 5-10 years from market. From 50x faster CPUs to super capacitors. That's just 1 thing.