I wonder if age has anything to do with it. As I've gotten older, not only has the idea of being bored evaporated, but the idea of other people feeling bored is borderline offensive. Life is short, time is precious, there's always a zillion more things that could be done (maybe productive things, or maybe just fun time-wasting things) than there is ever time to do those things. And then someday it's all over. I associate being bored with when I was a little kid, or even when I was in my 20s and it still felt like my whole life was ahead of me. When you've convinced yourself that your whole life is ahead of you, time feels a lot less precious.