The point is that, when technology permits us to automate production without or with little human supervision, that's the end of capitalism. You're not dumb, think. According to Marx, the only way that socialism and later communism will be adopted by society is when material conditions permit it. There might be attempts to establish a socialist or communist society at a national scale before conditions are ideal for it, but if such attempts fail that doesn't necessarily imply that socialism and communism will never work. It might have not worked in the past under certain circumstances, due to material conditions, geopolitics..etc, but it might very well work beautifully when the material conditions for its success are present.
Since when does an economic system or mode of production have to work all of the time, under all conditions? Why do the defenders of capitalism resort to these types of arguments? Did capitalism replace slavery and feudalism overnight? For centuries, at least from the mid-1500s, the merchant class with its fleets of ships and armies was in competition with the kings and nobles.
They were under the authority of monarchs and nobles until material conditions permitted them to assert their interests and liberties in the form of constitutions, parliaments, Republicanism, and privately owned business enterprises with an immense amount of resources and power, rivaling that of the kings and feudal lords. The industrialist class was born from the earlier capitalist mercantile classes.
In the future, our need for socialism and communism will become crystal clear when technology significantly or completely replaces wage labor. Adopting socialism doesn't equate to authoritarianism or autocracy, we can have democratic socialism and communism. The people hold the power, rather than a few billionaires who will own all of the technology, reducing 95%+ of the population to compost. Technology will replace wage labor, not because I say it, but because it's a brute fact. The pursuit of efficiency in production leads to automation and hence a loss of jobs. No jobs, or not enough of them, equates to a catastrophic crisis requiring a monthly government bailout called a "Universal Basic Income", in order to keep capitalism on life support. They artificially create paying consumers in order to maintain the market and continue making money. This leads to feudalism and slavery.
In modern socialism, we all own the technology, facilities, machinery, robots..etc (i.e. means of production), together, as a community. We then organize production, with all of its logistics, and accounting, using the best computer systems and data-gathering tools, to tell us exactly how many products we need to produce with the robots.etc. Each member of society that is able to work, works 20 hours daily, five days a week, supervising the system, and we all enjoy a very high standard of living. The alternative is everybody is a serf or slave to the billionaires who own everything. Techno-feudalism. I prefer modern, democratic socialism, where we all own the technology and means of production together.