On July 24th, the monitoring data showed that from the highest point in August 2014, the Ethereum hash value still fell by more than 42%. So far, Bitcoin and Litecoin have been the only currencies with a new hash value in 2019. BCH, BSV and ETH hash values are lower than their respective highest records. As of today, the one-hour 51% attack on the Bitcoin network costs more than $850,000, while the cost of attacking the Ethereum network for 51% of an hour is more than $100,000. BSV is the most vulnerable currency in mainstream PoW coins, and as of press time, the cost of a 51% attack is only $11,000.