When his neighbour discovered gold in a Californian river in 1848, Sam Brannan could have kept quiet about it. Instead, he filled a jar with gold dust and rushed around the streets of San Francisco shouting “Gold! Gold! Gold!” He had good reason to incite a gold rush: He owned a shop nearby. He became California’s first millionaire by selling picks, shovels, beans and bacon to the horde of prospectors who heeded his call.