Investors should eventually get used to the fact that the market is always volatile. And I think that volatility should decrease in the future. Most likely, the insane growth of the market remained in the past forever, but the probability of a catastrophic fall has decreased.
In 2017 people buy tokens only for speculation to sell them at exchanges on higher price. But during 2018 cryptocurrency market falled and now people carefully study the project and its perspective.
The market cannot endlessly speculate tokens so the market fall in 2018 was so deep. Now projects that simply issue tokens are not needed by anyone. We need well-working projects with the final product.