Overconfidence can often lead to ineptness

I had been leading a student technical team in my college, which was designing and manufacturing an electric vehicle prototype, so when I heard that a professor was offering a graded project to build a modular electric wheelchair, I jumped on the opportunity. There were three of us in that project, and all had the experience of more than a year with designing electric 4 wheelers, so making an electric wheelchair seemed like a piece of cake. We were required to prepare and submit a list of materials and components to be used so that they could be ordered accordingly. But since we were pretty confident, we chose the major components like the electric motor, motor controller, and the battery pack without designing and simulating the whole system beforehand to test their compatibility. When the parts and we started bench testing the electric power-train, we initially faced some issues which we disregarded as minor problems since we managed to fix them.
Since we had not planned or designed the entire wheelchair beforehand, we had to improvise to solve the problems presented to us constantly. Changing the whole design of the frame to help in assembly and modularity, and changing the materials, due to procurement issues were just some of the major hindrances.While integrating the electronics, both the motor controllers’ fuses blew off, and we had to order another pair. All this resulted in us being unable to complete the project in that semester, and while the professor was considerate enough to give us good grades, I still considered it one of my biggest failures.
This failure was not from the fact that we didn’t know how to make an electric wheelchair, we definitely had the knowledge and skills to do so. But because we had experienced in the domain and had even achieved a national rank of 2 in an EV design competition, we had become complacent and not given enough attention that a new project demanded.
I realized that every single project, even if they seem similar, has its own requirements and challenges which have to be paid attention to and diligently planned to ensure perfect execution. Through this incident, I experienced that overconfidence can often lead to ineptness, even if one is perfectly capable.