In the classroom, the boardroom, and at the speaker’s dais, the former chair of the joint chiefs cashes in. SINCE RETIRING FROM the military last year, former Chair of the Joint Chiefs of Staff Army Gen. Mark Milley has become a senior adviser to JPMorgan Chase bank, joined the faculties of Princeton and Georgetown, and embraced the lucrative paid speaking circuit. From military pay of $204,000 a year, Milley is sure to skyrocket to compensation in the millions, especially because he is represented by the same high-powered speakers’ agency as Hillary Clinton, who faced criticism in 2016 for her paid...