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 
if you already make a profit on the altcoin you bought better to sell it dont wait for much bigger profit like what happened.to me i waited for much bigger profit and in the end i lost. just to be gratefull and keep your profit while you have been get it, not want to more.