Recent startup failure was ZguideZ - an app that allowed locals to create their own digital tours, charge what they want, and then collect the majority of the profit on tours sold.
It failed because it was a far bigger project than I was able to manage as a solo founder - though I tried. It was beyond my ability to code it and I didn't have funding to recruit quality developers. I hired a budget team and we cut corners to stay in budget. I was unsuccessful in recruiting a team - partly because I had taken on a cofounder who decided he would rather surf than work on the business development end of our product - without a founder agreement, he was dead weight that scared investors and potential team mates away. In desperation for help, I began working with a veteran who had recently separated from Army intelligence - he had undisclosed mental issues and when our business plan was made a finalist in a university bizplan competition, he accused me of being a spy sent to retrieve classified information from him and sabotaged our meetings with investors, potential hires, and the competition administrators. He withdrew us from the competition and sent out insane accusatory emails to our bankers and advisors.
I attempted to carry on but the shutdowns of tourism in Hawaii and sheer exhaustion over my co-founder mistakes led to shuttering this project we thought would be the next AirBnB.
All told, this was a budget MBA program for me which ended up costing about 1/4 what a quality MBA would have cost me and probably taught me far more.
Lessons learned were:
1) the importance of a founder agreement
2) the importance of doing enough due diligence to understand the true scope of a project and then doubling or tripling the amount of work it will take to achieve that scope
3) the importance of working with the right people and refusing to settle when it comes to product or team