37 Signals has sustained revenue. They are not a startup in the same sense as YC or Silicon Valley thinks of a startup but they have the linchpin of a healthy business -- and every healthy business dislikes competition.
Not true. A struggling business dislikes competition. A healthy business likes competition. A competitor validates your market and frames a choice. With a competitor, a customer doesn't just have the choice of buying from A or not. A customer now has to consider buying from A or B (or buying nothing). When you've got dozens of competitors, you've got a market.
(Yes, I am aware that Guy Kawasaki marketed the Apple MacIntosh at launch.)
From wikipedia: "Lifestyle Businesses are businesses that are set up and run by their founders primarily with the aim of sustaining a particular level of income and no more."
And that's great if you want to create a business that sustains your lifestyle.