If we turned on a garden hose and used that constant rate of water to fill up a barrel, but I drilled holes in the side of the barrel, the hose would begin to fill up the barrel, but as the water got higher, more of it would begin to leak out.
grasshoppers), let alone what is invisible to the naked eye (e.g. No consistent amount of C14 has ever been calculated in the atmosphere, nor is it possible for mankind to do such a thing without having a device that, at minimum, spanned the circumference of the atmosphere.
You would literally have to be all places in the world at the same time in order to confirm the presence, or non-existance, of grasshoppers in all locations.
If you cannot be omni-present, which would be required for such a feat, then all you can do is put a guess on the number.
When the water reaches that steady state, it is called equilibrium.
C14 is continually being made by the sun's rays striking nitrogen (water pouring in), and continually decaying from the half-life mentioned earlier (water pouring out).
Once viewed in this light (no pun intended :), it seems childish to make these assmuptions without any credible historical evidence backing it.