RL. Being an adult gives you less time to spend on time heavy space games. I remember when I could just come home from school and spend hours roleplaying, writing stories and creating lore.
I'd also say it's because the 'glory days' are gone now. There's low pop, consistently lackluster/bad (subjective) updates and stagnation when it comes to story, faction, and regional progression. I'm also struggling to knuckle down and finish stories because I've got writer's block and lack of motivation.
Lastly, there's a lot of other games to play out there that are not only kinder to my time schedule but are also more enjoyable imo. That and I've got other hobbies I like to pursue.