Are you talking about micro businesses and we're in a niche specialty? Well, if that's my specialty, I'm not sure I would completely change my career path because it happened to be the same path as a friend's. But if my friend went into solo practice, I wouldn't jump ship at my current job and just copy cat what friend was doing.
If you mean competition as in Deloitte vs McKinsey, then my friend would not even be a consideration because the competition at that level is above my pay grade and I trust neither of us would take it personally when one of our firms wins over the other.