I agree, just as there are many definitions of "success" there are many definitions of failure. Here, I have an optimistic view of failure, as in the startup h

I agree, just as there are many definitions of "success" there are many definitions of failure. Here, I have an optimistic view of failure, as in the startup has to close doors with a profitable exit. Even if the startup had a positive impact on customers and the world, I'd classify this as a failure (because of failure to sustain).