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??
The most important thing before investing is to learn about the market and understand the purpose of the coin or token before investing as there are many coins aimed at just dump and pump and since this is a unregulated market expect these kind of coins and make sure you only invest in top coins in the market rather than going for dump coins.