Because block rewards are in a fixed amount of cryptocurrency, not a fixed amount of USD or similar. As prices increased on cryptocurrencies, block rewards beca

Because block rewards are in a fixed amount of cryptocurrency, not a fixed amount of USD or similar. As prices increased on cryptocurrencies, block rewards became more valuable - but not because the miner was issued more crypto. These energy consumptions concerns wouldn't be as relevant if ETH was worth 0.01 USD, for example.