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're gonna lose so much if you do that only some can do it right. Many investors have planned it out but never have done it right with precise timing and knowledge. The best way possible is to buy at a low price. Selling and buying later never comes out good.