Nihilism is known to be the process wherein the people believe that life does not have any meaning. They do not think that life has to be lived in a certain way because life just goes on for them. There are some who believe that there is no such thing as morality. They do not believe that there is a need to be moral in this world.
Their accepted belief about life itself and morality is a bit twisted in some people’s opinion but they believe that everything is perfectly fine that way. There are also some who consider themselves nihilists because they do not care about religion.
In psychological terms nihilism is a state of embracing nothingness: everything relating to the self is meaningless, transient, futile or non-existent. Nihilists are not fun company. These beliefs naturally produce anxiety and depression.
If the worst possible scenario is assumed, what is there to look forward to? Why exist, if we do exist, if there isn't some great force about to wrench us out of existence. That is how a nihilist might think.