Season 5 is nearly two-thirds through. The Hardcore players I know return at the start of the season, grind it hard, until they rip or get bored then move onto another title. This usually lasts for a week or two at most. If you're having a particularly good time you might extend this to four to six weeks. After three to four weeks there is a noticeable drop off of players. For example the Reddit HC community had 1000+ online on the first day and by week three less than 100.

Diablo 3 has always been a softcore focused game from its casual nature and that mainstream popular players all play in that mode. If you want people to play with you have to actively get involved in a Guild or some Communities. You find people and add them to your friend list. But the casual nature of D3 means some of these people may not return for the next Season. The key to HC for me was getting involved in a Community that allowed any HC to join so you weren't limited by just your Guild.

May I mention that other ARPG? Path of Exile has just had a major expansion and is friendlier than ever. It has more of a focus on Hardcore with its ladder race to 100, global reporting of deaths in the Top 50 and all the popular streamers there only play Hardcore. There is much more of challenging endgame. D3 to me is like that vacation you take when you got want to get away from a serious ARPG which is PoE. This is my own opinion but every HC players I know worth his salt is over in Wraeclast theorycrafting, pushing to 80, 90 or 100 and wondering just what level they should attempt the new Labyrinths in which you can rip in.

Set your own goals in D3, complete them, and just move on to the next title making sure you return at the start of Season 6 to experience the full HC population.. in the meantime I truly recommend PoE HC Perandus -- even Quin69 is streaming it now.