Mostly the pump and dump altcoins are happening below the 200 coins in terms of market capitalization wherein the market participants is only few, I do not participate in that kind of pump and dump even there is opportunity because for me the risks are too high because it is manipulating by the whales where one wrong mistake, I can lose all of money. It is easy to make money there but it is easy to lose money there so I still prefer to make investment with altcoins that have potential like XRP and ETH.
The only people that are interested in pump and dumps are the ones that know they have no chance by trading in the traditional way, after all if you know that you can make profits trading bitcoin and ethereum even if the profits are never going to be as good in the case you are lucky to get out of a pump in time the risk is simply not worth it, anyone that is remotely good trading bitcoin can get 10% or even 20% per year and while this may not seem much for some that is enough to make you rich on the long term.