With such grups you are chaising tail. and only leader of pump is getting hard cash rest most likely will sponsor his earnngs. You will most likely loose money there.
That's correct. Rarely a public pump group works in the long-term. Mainly because the manager of the group which usually is the guy who starts the pumps, probably has already bought amounts of the selected currency and will always try to profit from the new users and beginners mistakes.
I can speak of this from my own experience because I was already part of a group like this, and it never worked well.
The best way to organize an artificial pump is with a private group of whales that own a large amount of BTC, and are willing to allow the whole group to profit, controlling their greed to avoid disasters.