That's true I actually didn't know Ethereum halved their block rewards in januari this year, I just looked it up, and yes that makes a huge difference.
So the only people who are mining this are people with super low electricity costs or people who think Ethereum is going to reach a better price again.
Personally I definitely think Ethereum is undervalued at the moment especially with the rewards that halved but that's just my opinion.
When eth hit $1400, block reward was 5 eth, now as the block reward was reduced to 2 eth, if you think about, eth can reach 60% more than $1400 if bitcoin reaches 20k again, so $1400 + $840 = $2240 but I do believe eth can reach higher than this, if btc hits $20k again then eth will be around $3k by that time, 10 times higher than now.
I think Eth has room to run, but not like it did in Jan 2018. Shitcoin ICO mania isnt going to pump it like that again.