If power were a prescription drug, it would come with a long list of known side effects. It can intoxicate. It can corrupt. It can even make Henry Kissinger believe that he’s sexually magnetic. But can it cause brain damage? When various lawmakers lit into John Stumpf at a congressional hearing last fall, each seemed to find a fresh way to flay the now-former CEO of Wells Fargo for failing to stop some 5,000 employees