I entered Crypto market for 2 months and usually see the term "pump and dump", and some P&D groups. But i wonder they pump by selling and buying themself, so when price go up, who will buy it for them and they sell that for who???
With Blue-chip coins, someone could buy when it've pumped already because of good news. So with trash coins, who'll buy this pumped coin and why many PP&D group still live until now

Pump and dump groups most of the time have two layers, they have the leaders that know beforehand which coin they are going to pump and there is the sheep that obey what they are told, the leaders buy the coin they want to pump for cheap prices trying to not make the price rise too much, then they give the signal and the sheep begin to buy then the leaders sell and they get money, most of the time the sheep lose money but if an even greater amount of people get interested in the coin then it is even possible that the sheep earn some money too, it is a scam and you must avoid it.