One of my dearest friends is an absurdly smart person who works in a super-technical, intense science field. This person is also bound to be about an hour late to any hang out. As it turns out, smart people all tend to have some bad social habits. It's nothing to take personally. It's just the way their brilliant brains work, and that's OK.
Although highly intelligent people may be successful in other aspects of life, they aren't perfect. And sometimes, the social realm is where these mistakes show up. If this sounds perplexing, there's a pretty simple reason. "It’s because being social and contributing to a conversation is not a problem to be solved by thinking. It’s more about an energetic and spontaneous expression of how you’re feeling," wrote Sean Cooper in The Shyness and Social Anxiety Guy. You can't really study ahead of time for a totally off-the-cuff convo.
That said, this whole list is great news for anyone who happens to share these habits. Now you can claim that your lateness is only due to the fact that you're super brilliant. Whether anyone actually buys that excuse is another question entirely, but hey, at least you can try.