An entrepreneur is a person who has possession over a company, enterprise, or venture, and assumes significant accountability for the inherent risks and the outcome. The term is a loanword from French and was first defined by the Irish economist Richard Cantillon. Entrepreneur in English is a term applied to the type of personality who is willing to take upon herself or himself a new venture or enterprise and accepts full responsibility for the outcome. In common understanding it is taken as describing a dynamic personality. (Wikipedia)
If we understand that the Product Owner shall act as an entrepreneur, than we also see the contrast to typical management functions. Most managers do not risk anything. It is not their job. They ensure that people do their jobs according to processes and organizational restrictions. In contrast to this an entrepreneur builds something new. He believes in the future. He risks a certain amount of resources (money, people, …), in short capital, because he believes that the future will payback this investment.
If you work in the role of a Product Owner: Ask: “Do I have the possibility and the willingness to risk a Sprint?!” If your organization does not give you the power to decide if something goes into the Backlog or not, than you are not a Product Owner.