The entire monetary system is built off the idea of trading goods and services that are the products of human labor. Things like automated assembly lines are a precursor - when we had 3d printing, you remove all human factors in the creation of goods besides the raw resource acquisition, and sufficiently advanced printers can also decompose trash into reusable pieces so you don't even need raw materials any more besides power.
All our financial woes and economic malnourishment is the product of this system, beneath government welfare overspending the budget, it is why corporations post record profits while laying off thousands and why all that money goes to the top of the management. When the actual consumable and usable goods are not produced by people, the sale of individual units breaks down.
Look no further than media. Media is an upfront cost of creation, but reproduction is free. The current system is so broken because it tries to charge per unit as if unit production has an associated cost, where the cost is the funding, not the distribution. That problem only gets worse as we automate everything more and more (automated cars replace drivers, 3d printers replace small scale manufacturing...).
That leads to a big one. Automated mining and farming. Fully, with no human intervention, where you can set off a robot with some pre-programmed track of land to till or dig and it will extract all the resources from that area for you. Once that happens everything goes out the window, because a single point of sale unit of production (plus maintinance, which then gets ursurped by the singularity making machines improve themselves) where once one of these machines is available, resources are no longer scarce.
And then money breaks down. Because when human effort is no longer involved in the day to day operations of goods production, there is no continuous "cost" involved anymore, in the terms the Reddit thread describes, or how most people interpret goods and labor.