Because when there is a pump or dump, the market volatility will be high and the volume will certainly be high.
It's easier to trade during such conditions because the opportunity to get a better profit.
And you are right, this fluctuation seems to give an advantage to us and this is a way to make us more profitable than of stable market. And I don't think we need to wonder and asking to put this to an end cause it surely won't happen.
One can take advantage of this volatility sometimes but in the long run it is not good for the crypto market. Bitcoin adoption as main payment system can never be a reality if bitcoin keep moving up and down like that. This volatility needs to be replaced with stability for betterment of crypto market.