How so? The blockchain hasn’t ever been hacked. Or counterfeited.
Because of how people spend money. If people are broke, they are going to spend their money closer to bodily needs. You need to eat, wear clothes, travel to work, heat your home, etc. That’s where commodities come in. The more troubled the economy, the more basic the spending. In a 1930’s type depression, a bag of beans and rice are more valuable than shares of Coca Cola.
As people become better off, the become more luxuriant in how they spend money. This is when people start branching out into less secure investment opportunities, like stocks and bonds or cryptocurrencies. They can more afford to take intelligent, but risky, chances. The more secure people are financially, the more they will invest without security. If Bitcoin goes belly-up, you will not get any money out because there are no tangible assets.