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

You don't understand how it works when they pumped the coin, the price starts increasing and if you are online at that point in time you are just wondering how its increasing and the exchange site with statistics will show you how that coin has done in the last 24 hours. People who buy are those who believes that as it is increasing, I can hop in then cash out no knowing that the upward turned is artificial and cannot only be sustained short term.