Scenarios of the Great Filter are abundant, to be sure, but Helmbold (see https://www.amazon.com/Key-Victory-Machine-Learning-Lessons/dp/B09XJGQ6DD) describes in length how bitterness, casualty fractions, and intensity of battles have followed a startlingly steeper declining curve since 1930s.

An interesting read overall. Helmbold, being in his 90s, seems to me remarkably quick, ingenious, and meticulous thinker.

Could be quite a solid defense secretary somewhen in the worldline where, say, Kerry won in 2004.