RIVERSIDE, Calif. — The regulars did not take it seriously when Enrique Marquez mused about terrorism at Morgan’s Tavern, a dank dive bar where the bespectacled 24-year-old hauled ice, cleaned bathrooms and checked ID’s at the door. After a few drinks, he would just start talking – about his money woes, trying to lose weight, wanting to join the Navy. News reports about terror were just fodder for more bar talk. “He would say stuff like: ‘There’s so much going on. There’s so many sleeper cells, so many people just waiting. When it happens, it’s going to be big. Watch,’...