Molson Hart

At both Viaweb and YC, every minute I spent thinking about competitors was, in retrospect, a minute wasted.

Nah. To succeed you need to compete asymmetrically. To compete asymmetrically, you need to understand, from the customer's point of view what your value proposition is relative to alternatives.

Do you suppose this is why Tolkien sold more books than most other novelists?

I don't write books, I build companies. There's money to be made copying, differentiating from, hiring from, buying out, and underpricing the competition. At almost every stage of a company's life, the competition is highly relevant.