Currently I own a lot of altcoin, I bought them at ico. My account is being downgraded several times. There are many people who say bitcoin will continue to decrease, so altcoin prices also decreased compared to USDT. So now, should I sell them and wait for the price to buy back? Give me advice 
Many tokens return to the original ICO price after a while. Maybe it makes sense to wait. Of course, I'm talking about quality projects that really do something. Hold those coin you think a potential coin, but if the coin you have don't have a future I suggest you to sell it immediately that you already lose your money.