I'm sure the majority of the people living in Europe or the Americas in the 18th century didn't think that they needed a different economic system either, but capitalism ended up raising the floor of poverty in the next hundred years, as well as the ceiling of wealth.
That's a bad example since enough people in the 18th century wanted another economic system so badly the French king lost his head for it. Classical liberalism in general was popular in Europe since getting rid of church property and reducing the ability of the crown and high nobles to do what they want was good for the merchant class. But it was indeed very bad for the peasants. Liberal reforms in some countries like Spain and Portugal reduced the literacy rate and wealth among peasants in many areas for almost a century. France really only avoided the same from liberalism because Napoleon's wars killed an entire generation.
'Better' is easy to define: higher standards of living and longer lifespan. The poor of today live longer - and better - than the poor of yesterday. As do the middle class, as do the wealthy. There is no time in history where any particular economic class was better off than they are right now.
That's not really true. I recall an article on some poor, depressed Appalachian county (Boone County, Kentucky, at the time had the highest proportion of people on welfare in the country) where a guy the journo interviewed claimed it was easier to be poor decades ago. Minimum wage peaked in the early 70s, which most people didn't make because they had a union. Average wages have been fairly stagnant since 1973, despite an enormous increase in productivity of the average American worker. Despite all the tech and benefits capitalism brings us, somehow cars and especially houses are more expensive than ever. The truly poor are still living in shitty projects/Section 8 junk built 50 years ago, sometimes the same places their parents and grandparents lived. And this isn't just America, this is the entire West.
Those improvements have been progressing for a very long time, and they're not strictly related to any economic system. The life of the average person got better over time before capitalism, it got better over time after capitalism became the dominant economic system of the world, and when capitalism stops delivering and starts to backslide and the average person's life starts getting worse - another economic system will emerge to make sure that Line Go Up on lifespans and living standards.
Capitalism wasn't the only solution for that. For instance, the Indian state of Kerala, routinely governed by socialists and communists, is toward the bottom in India in terms of illiteracy, malnutrition, etc. and has consistently high education and a disproportionate amount of doctors. Cuba is famously like that too, even if Western commies routinely overstate how good Cuba is, the stats are more or less accurate and even the shitty doctors poor rural Cubans get are better than what they got back in the 50s and earlier. Both are definitely poor places, and are unlikely to progress much further due to the limitations of socialism compared to capitalism, but in certain fields communism can produce beneficial results.
And line going up is not necessarily good, especially when it deals with technological progress. Transhumanism will obsolete humanity and turn us over to the global cyborg elite. You can laugh at that, but that's what Yuval Noah Harari, Ray Kurzweil, etc. believe and advocate and these guys have the ear of the most powerful people in the world.
