Seems like we're in some kind of time warp here. I understand that with modern technology, things can happen faster, sometimes much faster. But how does spending 3 days determining that a business is not viable constitute a failure?
I really hate the whole "failure is OK" meme. Sure, we all understand that not everything goes perfectly all the time. But we also have those "Is this really worth it?" moments. For some of us, this happens all the time - the harder the project, the more often if happens. Sometimes all that separates real success from real failure is pushing through these moments, determined not to allow speed bumps to stop you.
I'm not suggesting that we will never fail or that we should never give up; sometimes that does make sense. I am suggesting that success is elusive until we adopt a personal policy of "failure is not an option".
OP was not a failure and not an example of this.
Failure is not OK.