On Finishing "Neither Here Nor There"

At the beginning of his book, Bill Bryson never states exactly why he took this cross continental trip. He did say that he travelled across Europe as a young adult and wanted to go back to appreciate it yet again as an older man, but the first time he went with his friend, Stephen Katz. This time he did it entirely alone. Here is my question: Why would anyone want to backpack across Europe for an indefinite amount of time alone? What could be enjoyable about that? Certainly, I can understand wanting to spend an afternoon alone, a day, perhaps even a weekend. But I would never ever want to go to a foreign country where I didn't speak the language and have absolutely no one to rely on but myself. Doesn't Bill Bryson enjoy human companionship? He even left his pregnant wife at home! Why couldn't he have waited and taken this trip once she had their baby and had a lovely family vacation? I suppose it makes sense that perhaps his wife wasn't interested in traveling in an unknown land for that long, so maybe that was their compromise. He could have, however, travelled with a friend who was interested. Maybe even Katz again. Or, he could have gone and done whatever he wanted in whatever countries he wanted and then met his wife (and possibly children) in a more family and tourist friendly city. I just don't understand how he stayed sane. He couldn't even communicate with many of the locals. I just don't get it.