Even if an entrepreneur is doing everything else right, committing even one of these mistakes can seriously damage the startup’s credibility and chances of successful launch.

You’ve got a product and not a business.
It’s still a science project.
We don’t have any competition.
Build it and they will come.
Competing on price.
Relying on one or two key strategic alliances.

https://www.behance.net/gallery/56936027/Rand-Robison-Stupidest-Mistakes-Entrepreneurs-Make