Capitalism is merely a system of private ownership of land, labor, and capital assets - versus other forms of ownership of the means of production. Each - land, labor, and capital assets - can be put to use to acquire money to invest in land, labor, and capital assets. If you look in a dictionary, that's what you'll find.

In the early United States (after having committed killed and driven off the Native Americans through war and genocide), there was a lot of land. Yes, this was forcibly acquired. Labor was a not scarce, but it certainly tended to be worth more. That made it so that wages (though low) could be used to buy land within a few years for those who wanted to farm or start towns.

Things became more desperate when labor became cheap through the massive immigration of tens of millions of workers. However, the rise of labor unions to strike for collective bargaining, and the rise of the manufacturing sector in the United States to supply goods and services to the rest of the world - especially after World War II, when much of the rest of the world was devastated - led to greater prosperity for the average worker.

That changed when the rest of the world's workers demonstrated their cheapness and there were technological breakthroughs in containerized shipping, telecommunications, and computerization/automation. Today, labor unions today only have strength in areas where the work cannot be outsourced or automated - hospitals, governments, school districts, police, etc. - or where their membership power remains due to having a lock of some kind (though a shadow of what it was in the past) - auto manufacturing, mining, port facilities, etc.

Ultimately, under a socialist or communist system, there can be a job for everyone who wants one. Some even think maybe society should give a job in graphic design or film or music or art to every one of the 1 in 17 Americans who graduates each year with a degree in the Visual or Performing Arts. Or that everyone should get to go to college and should get to have a good job after graduating. And heck, I certainly wouldn't mind working just 20 hours per week, or mind getting a free income - I'm tired of day after day of working! There could even be make-work and bureaucracy to make everyone look busy - that was practiced in much of the former Soviet Union. (Yes, I'll even allow that some might say that wasn't "real" socialism, or "real" communism.)

But it would be very costly. Both in terms of productivity per labor cost input, and productivity in terms of economic competition against other countries that have far lower labor costs. What you would need would be a closed system of high tariffs to fight imports of cheaper goods manufactured in other countries.

The other factor to fight is human population growth - from both reproduction within one's own country and immigration by the millions into one's own country. The more people you have, the more wealth you need to generate to provide for those people: jobs, homes, resources, etc. If you're paying people to be able to afford goods and services, but reducing their number of hours worked or removing their need to work or giving them jobs in fields where they really aren't needed, it helps to have a set annual cost that only rises with low inflation in tandem with the income from tax revenues - not an exponentially increasing cost that rises faster or depends on raising taxes! But paradoxically, usually the same people who want shorter work hours for the same pay, or a job for everyone, and state-provided home, food, shelter, care, education, income-support for everyone... Are also the same people who want increased immigration despite immigrants being mostly low-skilled, low-wage, less-educated. And are also the same people who want no restrictions on reproductive freedom... And also the same people who want society to pay to provide for those who have children they can't afford to raise.

So what you'll find is that other economic system, even a socialist or communist one - where strictly, the state owns land, labor, and capital - can have serious drawbacks...