What do they mean when they say "no diminishing returns?" does this essentially mean the code you are testing has no bounded state space and you continue to find infinite paths?

Because we have tools and techniques that can guarantee the absence of certain behavior in a bounded state space using formal methods (even unbounded at times)

Sure, it's hard to formally verify everything but if you are dealing with something extremely critical why not design it in a way that you can formally verify it?

But yeah, the easy button is keep throwing more tokens till you money runs out of money