It is not a loss of popularity, it is just market correction that usually happens followed by a big growth. That's the process when the market reacts to things it is reluctant to. Here is a list of events that made the prices crash:

Chinese New Year.
Many people in China sold their cryptos to cover the New Year expenses.
China threatening to ban cryptocurrencies.
Worldwide banks blocking cryptocurrency transactions through their Credit/Debit cards.

Those events made the marked to crash but not collapse, it is recovering now and will get back stronger and better!