You like to define it as a new, for-profit business. Seems reasonable. However, I found that many others use the term to specifically refer to the kind of high risk, high growth company that meet the investment profile of typical venture capitalists.

It seems obvious that the good people of startup school are using the word startup in the latter sense. And honestly that sense of the word seems more common. Most people refer to what you do as bootstrapping, not a startup.

But is it really that interesting to have an argument over the definition of startup?

I don't think anyone at startup school is against bootstrapping. They're probably not against enterprises either. The event just has a focus.