Just before the surge in 2017 there was a time of maximum pessimism where most coins were worth nothing, then many went up 100 x or more.
This is true, but also true is the fact that from time to time a coin had it's move up. Now this isn't happening anymore. Only some ICOs go up pumped by investors money.
A lot of coins are dead because the price or volume killed them (delisted from exchanges) or abandoned by the developers just because they worth nothing or the money run out (ICOs).
The most classic reason is that they made an ICO just to make a profit, after that they left and returned by making the same project. All of that was organized so I'm not surprised to see a phenomenon like this.