https://www.forbes.com/sites/ktorpey/2019/09/30/this-cryptocurrency-just-surpassed-bitcoin-in-one-key-adoption-metric/#7a7300d17e2f
...Due to the limitations placed on capacity, cryptocurrencies like Bitcoin and Ethereum see higher transaction fees when the networks become congested. This is exactly what has happend with Ethereum over the past month, as total daily USD-denominated transaction fees hit levels not seen in over a year.
So, what has caused the recent spike in Ethereum transaction fees? It appears the blame can be placed on a Ponzi scheme-esque game called FairWin, which also has a critical vulnerability in its associated contract on the Ethereum blockchain. According to on-chain crypto market analytics firm Glassnode, FairWin has recently been consuming up to half of the gas spent on the Ethereum network at any given time.
The spike in FairWin's popularity, according to Etherscan, correlates almost perfectly with the increase in total fees seen on the Ethereum network this month, according to Coin Metrics.
At some point miners might decide to switch to Ether, especially as Ether provides block rewards in perpetuity as well (no halvenings).