I heard that too. There are large pump and dump groups. These people buy a big share of a coin, pump the price and then dump it.
People who buy on high prices are destroyed because the coin never recovers from the dump. I have done two mistakes in the last week of July. Synx and RNS coins. I bought at high prices. Sold one at loss. The other one is 7 times below the price I bought at.
I have no option other than waiting for it to recovery losses.