An enormous factor here is the cult of speed. This mantra — performance above all — has touched every generation of programmers. The zero-overhead zealots, the minimal-runtime purists, these camps are not only present, they are crowd out every other perspective. It's not that their arguments are entirely unfounded. Language choice does have a causal effect on application performance. The issue is that these voices drown out all others.

The root of the problem is measurement. Speed is one of the few dimensions of software that is trivially quantifiable, so it becomes the yardstick for everything. This is textbook McNamara Fallacy[1]: what is easy to measure becomes what is measured, and what is not easily measured is erased from the calculus. See developer velocity, cognitive overhead, maintainability, and joy. It's the same fallacy that McNamara made in Vietnam and Rumsfield made in the War on Terror so at least they're in good company.

This singular focus distorts decisions around language choice, especially among the inexperienced, who haven't yet learned to recognize trade-offs or to value the intangibles software process. Like you said, humans are irrational, but this is one particularly spectacular dimension of that irrationality.

1. https://en.wikipedia.org/wiki/McNamara_fallacy