pump and dump groups have happened before.
the moral of the story is.. the person shouting the buy signal to members,, already bought before shouting buy... then waits for everyone else to push the price.. and then the organizer sells right before shouting to everyone else to sell..

end results.. only the organizer makes noticeable gains while everyone else is panic buying and selling in the middle..

it does not help cause any real long term rises. and just causes crappy speculative spikes..

if your going to do it.. do it with the pennystock (altcoins)