Preppers is the collective name given to those that devote some of their time to preparing themselves and their families for the apocalypse. People can allow this to consume their whole lives, devoting vast amounts of resources to an apocalypse that may never come. Common actions of preppers include large stockpiles of weapons, food and water and the construction of fortified bunkers.
People become preppers for various reasons, some of them founded in reality, many of them not. There’s a TV series on Netflix called Doomsday Preppers where the people taking part give reasons such as an impending meteorite impact, the magnetic shift of the poles, implementation of martial law and nuclear war. This has become quite a big industry in the last few years with vast catalogues containing everything you might need to survive any scenario.
People can plunge their entire life savings into preparing for what they see as inevitable. This is more common in America where fear of the government and belief in conspiracy theories are much higher. Alex Jones also hawks survival gear on his website, so he can point you to the right thing to protect yourself from the threat that he just told you about. Having some batteries, torches and water around isn’t a stupid idea but devoting your life to an apocaylpse that might not arrive is.