This statement is ignorant of a new class of cryptocurrencies called "Stablecoins". Stablecoins are always the same price - they never go up or down. For example, the price of DAI, a stablecoin, is always "soft-pegged" to $1 USD.
Stablecoins such as DAI are very beneficial and could one day bank the unbanked. Brining the ability for even the most vulnerable in society to save, earn, trade and participate in the global economy of the Internet.