Yes, there are. The Basecamp founders wrote books about it, Rework and Remote. The reason you don't hear more about them is that heroic work is more glamorous to discuss. It is worth following https://twitter.com/dhh
Basecamp is derided in the valley as a “boutique” business, one that does not take VC investments to take off like a rocket and become a unicorn.
If rarity is what makes a unicorn then they are more of a unicorn than the social media company du jour.
Actually, the only rare thing is the amount of media coverage non VC backed companies get. Because most profitable companies are bootstrapped smaller ones.