I suggest becoming informed and read about other economic systems yourself. There is a bit of ad hominem in your question. For many the materialist concerns of the current dominant economic system is why people complain. Those complaining aren’t the cause and should not be rebuked. The rich are getting richer and the poor; poorer. The chasm between the two only grows wider.
That said, many folks on the political spectrum would at least like to see the US end of neoliberal capitalism and a return to Kantian/welfare economic capitalism. You see flavors of this in European Democratic socialist countries, albeit even those are succumbing to neoliberalisation.
If you get into rights based discussion, many in that spectrum and further left would like to see positive rights enshirined constitutionally as well as the ERA. This would bring about many of those kantian economic mechanisms by default.
For many more on the left, we literally want to seize the means of production and distribute wealth equally among the masses. Bring about socialism to progress to communism. The DSA believes in a change and revolution from within, and have a national platform and a growing base. There are also the PSL, which demands a more revolutionary overthrow of capitalism into communism. Briefly put.