After attacking Monero $XMR , the next target is Dogecoin $DOGE ? I don't think this will necessarily succeed, although POW coins all have a common flaw that they could potentially be subject to a 51% double spend attack. However, a 51% attack on Dogecoin is generally considered highly unlikely and exists only in theory. The probability of a 51% attack is inversely proportional to the network hash rate of the blockchain. The greater the overall hash rate of the blockchain, the less likely it is to be attacked. For Bitcoin, as its network size continues to grow, the occurrence of a 51% attack is basically nonexistent.