Most Americans directly own stocks and a college graduate is even more likely to. This isn't the 1860's so a lot of these critiques of capitalism are anachronistic. The reality is "shareholders" are fairly ordinary people and not a tiny and mysterious group of elites.

First, trickle-down economics is a modern neo-liberal concept.

Second, most people just do not earn enough to invest a significant amount of money in stocks. It's a system that largely benefits the rich. The more money you already have, the more you can invest.