According to Yassine Elmandjra, a cryptocurrency analyst from ARK Invest, Bitcoin miners are now responsible for 80 percent of all mining rewards. BTC's share has increased by more than 250 percent since mid-2017.
As the graph below shows, BTC completely dwarfs other proof-of-work (PoW) cryptocurrencies, including Ethereum (ETH).
Ethereum surpassed Bitcoin by the total amount of miner rewards back in May 2017. However, its share started to decline in a very steady manner, which coincided with falling ETH prices.
During the Ethereum 2.0 era, the leading altcoin will gradually transition to a proof-of-stake (PoS) chain.