I have friends that were ETH miners way back. Their rigs became unprofitable for a while and they quit. 2017 was a heart breaking year for them having had so much ETH at one point and having sold almost all of it. Thankfully they held onto a little something however they really regretted giving up way back then. Its nothing compared to the guy who sold me his BTC miners in 2014 though. It seem every time someone quits someone else finds opportunity.