Law of diminishing returns does not always apply:
The law of diminishing returns states that in all productive processes, adding more of one factor of production, while holding all others constant, will at some point yield lower incremental per-unit returns.
I interpret "productive process" as a process that creates a product other than money.
Many productive processes can be done in parallel.
I see how it is true for any process with a central control, because that is limited by the interaction with the instances, so at some point adding a new instance requires additional changes.
But A productive process does not need to be centrally controlled.
If I run a snowball factory, I can add more workers, invest in required infrastructure like gloves, and send them out to build snowballs autonomously.
The central work does not only scale linearly, it even scales constant! The total effort summed up over all instances scales linearly.
To be strict, it scales exactly linearly because adding a later instance can not add less productivity than an earlier, because the earlier instances are not in communication with the central point at the time. The first instance does not differ from any other, because their creation does not differ.
If I would insist to earn money, the money transport is limited in bandwidth. We have freight trains, that's good enough. But there is also a limit in snowball to money conversion by market interaction, as a market is finite.
So, producing money is limited final market size, there can be a snowball I can not sell. Adding instances does not increase production of money.
But the production of snowballs seems to be limited only by the availability of snow and homo sapiens - by climate change.
What's wrong with that?
Of course, "law" does not mean it strictly applies always. Is it that I just constructed an example outside its validity? Where is it valid, if that is well defined? Or is the argument above wrong?