[unclebucknasty]

That's absolutely true. I think it's very common in the startup world to tackle fairly big problems with known challenges--armed with a set of hypotheses--only to be later stopped out by those same challenges.

But, how much confidence in our hypotheses is enough when it comes to the key "show-stopper" challenges? How clear should we be on the path before moving forward? Speaking from personal experience and observation of others, I would say that we founders tend to be optimistic when assessing these challenges at times. There's a little hope in there.

I suppose a certain degree of that optimism is necessary, else no one would move forward. It's just a bit painful to fail for all of the reasons you knew beforehand.

Because, testing the proposed solutions can be exceedingly difficult and resource-intensive. I've often wondered if there's a better way to test assumptions than just going all-in. I've found the much-lauded MVP approach to solving this doesn't cut it for me or for a lot of models/founders. For models that require things like network effects, brand credibility, and more advanced functionality to even be usable the "MVP" is, effectively, the full product. And, this doesn't even consider the marketing/PR/etc. that must be put behind it.

Given all of that, you actually did well to move on in only 18 months. Congrats on making a tough choice and freeing yourself up for the next opportunity.