I think it’s not really the right kind of game where a hardcore mode provides enough of a thrill that it sounds enticing to play. Because of that, there isn’t a huge player base, and when you don’t have a huge player base you get problems of not enough economy (gear available or fg value for drops) not to mention that it becomes impossible to find others to play with.
Realistically, it’s not scary to play HC because you think a super strong monster might destroy you… it’s scary to play HC because you don’t know how many years it will be working on a character only to accidentally enter a catacombs at lvl 1 when there’s a monster inside, or internet goes out and you don’t d/c fast enough to avoid dying.
It makes sense that many people would play it at the start because it was, in a sense, a new ladder where years of piled up gear didn’t exist… but that isn’t really the case anymore, so there’s some risk, sure, but not much reward to be had.