This is a question I've struggled to answer myself, even though I love it. Why do I love it?

But is the why that important? I'm not so sure. I'll try and answer it anyway.

When my time is nearly up, I won't care much about how nice my kitchen looked or what car I used to be able to drive. I'll want to know that I lived my life in a way that made me proud, and I'll want to look back and think, "Wow, I went on some wild and crazy adventures!"
When I'm on tour, I sometimes long to be home, and for normalcy - a normal shower, a normal wardrobe, a normal bed, a normal kitchen, a normal social life. But I never get sick of riding. So that's something.

I'm surprised at your comment about riding on a city bikeway. Cities all look the same to me. "Oh look, another building! WOW! I would've never expected that! Look at all this stuff to do! You can go inside and sit down and eat something, or you can go inside and sit down and watch something!!! I will never get tired of this!" Of course, I know a lot of people that aren't outdoorsy, and get bored to tears in small towns, much the same way I'm bored to tears in big cities. So it's a preference, I suppose.
And if you're not on tour, that's probably the same city bikeway, or at best, 2-3 bikeways, day after day after day...

I like the independence, I like the scenery (most of the places I've been, anyway), I like the challenge, I like meeting friendly people. If you ever get pessimistic about the nature of the human species, go on a bike tour and see the outpouring of support. It still surprises me every time, and at the end of every tour, I unexpectedly say my favorite part was the people.

And I like riding my bike. What's wrong with that?