They come back because ended free distribution of coins (fork), no one hacked them, i am sure that later there will be news that hackers took pity and decided to return the money =)

BenRickert
As soon as this shit broke, absolutely all coins fell complexity and dramatically increased the income this was the reason, and not that increased the price of the coins.

You little understand how NiceHash "works", more precisely, those who use it (buyers). You sit day trying to find a block, as soon as the complexity of the coin decreases i pour into your pool of several thousand miners for pennies who work for a bowl of food, taking away all your income. Of course, the complexity then increases again, and I leave you alone, while the difficulty doesn't drop again. And I repeat over and over again, taking away all your profit and making sometimes 300%. This service is a parasite for ordinary miners, he just should not exist. Almost all young coins are banally destroyed at the start...

Oh, wait, maybe you are buyer? The parasite, who earns on simple miners using the wretchedness of all cryptocurrencies?