There is no specific checklist that you can follow to become a tech entrepreneur. That said, very common topics include coding, accounting, engineering, math, wireframing, technical writing, and analysis. Depending on your company, there are countless other topics you might need to study in order to succeed.
The reason some tech companies have a lot of employees is that those companies do a lot of things. Software development can involve a lot of people in the project. If you add in tech support, marketing, expansion, and administration, it’s easy to see why there would be a lot of employees at any given time.
For the most part, this is done to get expert research and analysis that can help tech companies make informed decisions for many aspects of how they operate. Economists can help them understand consumer trends, international relationships, fair practices, how they are affecting the world, and a lot more.