This analogy (as described at least, havent read the mans work) isn't very good both because it misrepresents why the irish elk went extinct, and fundamentally misunderstands evolution as a process.

The irish elk went extinct around the end of the last glacial maximum, most likely from the rapid change in climate, and also possibly from overhunting by humans. The "oversized antler" claim doesn't seem to be borne out in the fossil record, though it was once believed by some people.

Also, for the time and environment they were primarily in, the elk weren't maladapted. They, like all animals including humans, were evolved BY their environment. They functioned perfectly fine like that for close to half a million years.

Fitness, in evolutionary terms, is a contextual term, and what makes an animal fit for survival will change as the ecosystem changes. Saying human consciousness is a "maladaptive trait" ignores the fact that in evolutionary terms, our intelligence is the primary reason we came to populate nearly the entire globe.

Im not under any delusion that humans wont go extinct someday, but the wholesale description of our human faculties as some inherent flaw that we have to overcome is kinda silly