It explains a fair amount.
In spite of the poor press, a stock market that is regulated like the Dow Jones is a good repository of value. It is not paper value, like government bonds, that the government can easily manipulate or repudiate.
Unlike gold, it is very liquid and portable. It is easy to access from most places in the world.
It is portions of real companies that earn real profits.
Of course, value can be diminished or destroyed by disasters, the same as can real estate. It is not as easily used to pay for small purchases in barter, such as ammunition or cigarettes.
But actually try to buy something with a gold coin. In spite of fictional accounts, you will find it far more difficult than fiction writers claim.
Gold has been money for over 3000 years. After the SHTF you can use your fiat money as tinder to start fires.