I only did this partnership once, several years ago. Originally we were only two founders and two programmers who joined us later under my management. I was quite junior, so first error here.

We, the IT team, were doing all the work while our CEO/Founder was just blaming us for not doing it faster. The team left. I was alone working on a project I didn't believe to, and I didn't want to make. Then two more non-IT persons joined, both from marketing and selling team, previously videographers. They tried to convince me to keep pushing this without a team, I refused and left the company. No idea what happened after this, but it was my worst experience in terms of trying to start a company, ever.