They are scams .  The people running them buy the coins days in advance .  They put their sell orders in well before they announce the coin to the suckers who get left holding the bag.  The entire pump lasts less than 1 minute.   


    The leaders buy for 10 cents and sell for 30.       

The suckers buy for 15-35 cents .   A minute later the price goes to 20 , so most people lose their coins to the people running the pumps .