There's some controversy around personality testing, with a common view being that it can put people in a box that they then play up to and never get out of. But used intelligently, it can help people to find the right role, or manage the stresses of their current role better because they understand the drivers of their behaviour.
For example, if you are essentially an introvert, all the networking and people management of being the boss may not play to your strengths and you may end up exhausted and demoralised at the end of the day.
But if you understand why that is, then you can take steps to make it work better for you - by, for example, hiring someone who is more 'E' than you to do the bits you don't enjoy, or promoting someone internally who you trust to take on that part of the role and free you up for what you are really good at. Your business will flourish as a result. Not rocket science? It never is, but sometimes, busy, successful people just need some time out to think about it.
Not everyone has the personality to be a founder, but more and more people are choosing to start their own companies because entrepreneurship is increasingly seen as an attractive and prestigious career path. In fact, roughly 66% of adults today are interested in becoming founders. As such, it is reasonable to expect that not everyone will have the entrepreneurial personality traits needed to become successful and happy in their jobs.