For example I mined 0,05 Ethereum 1 year ago with the Rx480 and it took me longer then a month.
Because The Total hashrate was a lot higher a year ago, so it could be possible now that miners are receiving more ethereum.
But I do think people do it because they actually believe in Ethereum and they wont just quit after one period where the market goes down.
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.