Every attack (on purpose or not) will have a negative influence for a while, but BTC will survive and come out stronger. The China ban caused a big selloff, but the result was that the market became more immune for government regulation (Chinese are still trading like crazy, but more underground). Attackers spammed the network and made transactions expensive for a while, the market came up with upgrades and batching and the network is stronger than before. The Jappanese whale started to sell off Bitcoins, the price dropped 70%, the Jappanese Wale got less rich and the Bitcoins are better divided between users, Bitcoin comes out stronger again.