Only insane in the context of recent decades. The vast bulk of jurisprudence (centuries) supported a much more restrictive reading of 2A, and changing that was a concerted effort of conservative groups (starting in the ~1980s), particularly out of more conservative law schools such as those in Tennessee.

This was pretty well documented at the time if you would like to read about it[0].

[0]https://www.nybooks.com/articles/1995/09/21/to-keep-and-bear...