Just look at Siacoin. Difficulty is not dropping despite losing $2-3/day net. I think plenty of people (myself included) would be more than willing to mine at a loss gambling that the price will go back up... Remember, it's not a loss until you sell.
SIA is on ASICs now, so it's not example.
https://obelisk.tech/Also SIA has infinite volume (there is no coin cap), so it is completely based on potential usability, not scarcity.