I wouldn't call him lonely, he had constant visitors from all over the world and his followers ensured him that his philosophy would not die out.

Moreover, the 'junkie' part is misleading in that it sounds a lot worse than it was in his day. Crowley had chronic bronchitis (decades of smoking will do that to you) and heroin was commonly prescribed in his day to help with symptoms. Not like he had to go to the street for his dose, he had access to top-notch pharma-grade heroin to use as he saw fit, something which isn't possible today. I'm quite envious actually.

All the strife and bad blood and still his happiness needs to come out of a needle. Maybe what the previous posters wanted to point out is that if he’d have cared more about his fellow man, he’d have made connections that are less shallow than the ones based on his excessively pompous prose or his other performative exploits. Maybe those visitors wouldn’t have stayed vistors.

Hard to say, personally my experience is that the junkie lifestyle seems less hollow and more appealing than it is, no matter the quality of the substance.