I think the language you use in this post is telling. Under a certain interpretation it's not exactly incorrect, but that framing doesn't really tell the full story.

Your main dichotomy is people doing stupid things vs people doing non-stupid things. But if you consider that "stupid" only makes sense with respect to a particular set of objectives, you may find that other terms are more suitable for characterizing the general situation.

I think you can roughly describe how many resources should be devoted to performance and correctness* as a function of 1. how many other systems will depend on the system in question, and 2. how much departing from the ideals in performance/correctness will impact individual users.

As both 1 and 2 decrease, an ideal development resource allocator would decrease the amount allocated to performance/correctness.

I would argue that making sacrifices in performance and correctness is not necessarily stupid behavior at all; departing from an ideal resource allocator would be the less smart thing to do.

*Assuming you're working with a resource pool smaller than what would be required to produce an Ideal product, as is typical.