Altcoins tend to crash to death because primarily, they're worth cannot be stated. Considering the market for altcoins is crowded, and most of these so called coins offer nothing of real value to be holded by investors, makes them prone to irrecoverable death. Their basically useless in the sense, but not all of them. ETH and other top altcoins still has something in them. Just don't expect altcoins to continue to grow or even surpass bitcoin in the next few years because it's highly unlikely to happen.