Many of them went bankrupt because they could not choose a good coin, many also bought only because they wanted a high increase regardless of the quality of the coins they bought, and when the market went down the coin coin would go down even further, ending in cut loss. So the suggestion is that I buy coins that have a clear project.
Even if they choose good coins, they are still at loss. Nobody thought that bitcoin and altcoins could have come so down as they are now. No one would have thought that we could drop from 800,000,000,000 $ market cap to 134,330,682,461$ market. In such a big collapse almost everyone would experience a loss.