Whether it be capitalism, communism, or socialism the system needs to reward risk. Risk-takers who build companies and organizations including those who invest in them should be rewarded for taking that initial risk.
Employees in such cases get the benefit of risking little and being paid a salary or taking off the top first always. But those who own equity get their share last yet take all the risk. So a system that promotes and rewards this risk will see the most growth and success.