Because Mother's Day
Coffee trees developed caffeine as an insecticide, to kill off bugs that would eat its berries and fail to spread its seeds. Yes, it's a deadly poison, but for tiny bugs. It takes at least as much coffee as crazy-face above is drinking to kill off us giant primates. Why Coffee is the greatest addiction (in every sense).
Though maybe my mom should drink slightly less coffee. Maybe. LIFE Magazine, Feb 2, 1953.