I learned almost precisely the same lesson in the same way over the same amount of time (a year) a few years back.
It was _incredibly_ helpful to have those insights going into my next startup, and I approached customer development entirely differently.
Lessons learned can be quickly applied!
"In hindsight, I took on an unreasonably audacious endeavor with Level in part because of my internal “this might get big if I play my cards right” dialogue. It would have been far better to either deliberately go for the big idea (and probably seek venture funding to make it happen), or start far smaller and build my way into a sustainable company of one."
I appreciate this passage... a thoughtful reflection.