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 
I think now the price of Altcoins in most ICOS is reduced after you buy them. So you should sell them early to avoid more losses. Then you can buy them at a cheaper price if you really believe that it is a good project and can increase prices in the future. The best thing to do is just wait for the price to dump and buy it in exchange, don't invest in ICO even if they give a bonus for early investors as the usual trend now, coin will dump more than 50% of its price, we should be smart and act where we can talk advantage.