I have been a Boglehead most of my life, interested in finances and planning since my twenties. Back then the retirement tools an ordinary person could get were close to useless, while the elegant planning tools lived only with the wealthy and their financial advisors.
Eventually one of the big brokerages took a stab at adding planning to its platform, but it never allowed the kind of analysis I wanted. Later I found a well-regarded planning service, genuinely a very good tool for the common man. What bothered me was the recurring annual subscription, and that all of my data lived in the cloud.
So with the skills I had picked up over the years, I built my own. Showing it to friends and family is what convinced me to share it.