no bro, they are not dumping to crash the market they are dumping to buy back cheaper coins, it's normal to have a correction in bitcoin and more so in altcoin
you don't know most of the time what the top is, otherwise we would all be rich already, my strategy is to buy when there is a continuos increase and to sell when there is a continuos decrease, with this strategy you don't remain off the market, and you have a chance to minimize possible losses