I once hold a coin and suddenly the coin that is almost $1 dump to less than $0.01 to me I move on but to some people which are newbies this can discourage them from participating in crytocurrency and make them conclude it is fraud and that brought me to a question how do you think pump and dump group are damaging crypto-currency and it's reputation??
I can't say that cryptocurrency groups of pumps & dumps harm their reputation. There is nothing illegal, and they use their money to raise or to drop the price. Another matter that the newcomers in these groups can lose because only those who are at the top are winners.