It's normal for people to lose interest in the forum and for new members to take their place. It's nothing new with online communities in general. I used to go on a Pokemon forum ten years back (oh wow, that's a long time ago), and all the other active members I was familiar with left and were replaced by a whole new lot. I ended up losing interest in it too, so I left as well. On TFF, I've had friends come and go throughout my time here. This is just another wave in the cycle.
Forum activity is a lot like in offline reality; people find new interests, or various events stray them toward another path, and they move on to newer pastures.
OT: I clearly haven't given up my love of Pepsi. I used to joke about being obsessed with it in my early days here.
Unfortunately, I need to part with it until I get my weight under control. I got one 2 liter to finish, and then it's time to attempt a healthier lifestyle.