Explanation
A product's success is measured by the value it delivers to the customers and the organization. The impact on cost, revenue, and customer satisfaction are three important indicators of value. The Scrum Guide states that
"The Product Owner is accountable for maximizing the value of the product resulting from the work of the Scrum Team."1 The Product Owner should consider the cost of developing and maintaining the product, the revenue generated by the product, and the satisfaction of the customers and users who use the product. These factors help the Product Owner to prioritize the Product Backlog, define the Product Goal, and collaborate with the stakeholders.
References:
1: The Scrum Guide2, page 6
2: The Scrum Guide

* The Product Backlog is an ordered list of everything that is known to be needed in the product. It is the single source of truth for the Scrum Team and the stakeholders. It contains all the requirements, features, functions, enhancements, fixes, and anything else that can deliver value to the customers and users of the product.
* The Product Owner is accountable for managing and refining the Product Backlog, collaborating with the stakeholders and the Developers, and ordering the items in a way that best achieves goals and missions. The Product Owner represents the interests of everyone with a stake in the product and ensures that the Scrum Team works on the right things at the right time.
* The Developers are accountable for creating a "Done" Increment that meets the Definition of Done each Sprint. The Developers are responsible for planning and executing the Sprint Backlog, designing and building the product functionality, testing and improving the product quality, and delivering a potentially releasable Increment. The Developers work closely with the Product Owner to understand and clarify the Product Backlog items, provide feedback and estimates, and suggest improvements and innovations.
* All planned work for the Product done by the Scrum Team must originate from the Product Backlog.
The Scrum Team does not work on anything that is not in the Product Backlog. The Scrum Team does not add or remove anything from the Product Backlog without consulting with the Product Owner. The
* Scrum Team does not accept or implement any requests or changes that are not in the Product Backlog.
The Scrum Team does not create any other artifacts or documents that are not derived from or related to the Product Backlog.
References:
* Scrum Guide: https://www.scrumguides.org/scrum-guide.html
* Product Backlog: https://www.scrum.org/resources/what-is-a-product-backlog
* Product Owner: https://www.scrum.org/resources/what-is-a-product-owner
* Developers: https://www.scrum.org/resources/what-is-a-developer-in-scrum

Explanation
A Sprint may be cancelled when the Sprint Goal becomes obsolete. This is because:
The Sprint Goal is a short-term objective that provides guidance and focus to the Scrum Team throughout the Sprint. It is a flexible and negotiable commitment that can be adjusted as more is learned throughout the Sprint.
The Sprint is a container for all other Scrum events and activities. It is a time-box of one month or less during which a "Done" Increment is created that meets the Sprint Goal. The Sprint has a consistent duration throughout a development effort and only changes duration between Sprints.
A Sprint may be cancelled before it is over by the Product Owner if they determine that the Sprint Goal is no longer valid or valuable. This may happen due to various reasons, such as a significant change in the market, technology, business direction, or customer needs.
A cancelled Sprint should be rare and exceptional. It implies a waste of time and resources that could have been spent on delivering value. It also disrupts the rhythm and flow of the Scrum Team and the stakeholders.
When a Sprint is cancelled, any completed and "Done" Product Backlog items are reviewed and potentially released. Any incomplete Product Backlog items are re-estimated and put back on the Product Backlog. The Scrum Team then plans for a new Sprint.
Other options, such as when the Developers determine the product plan is infeasible, when it becomes clear that not everything will be finished by the end of the Sprint, or when the sales department has an important new opportunity, are not valid reasons for cancelling a Sprint. They may reflect a misunderstanding of what a Sprint Goal is or how Scrum works.
References:
[Scrum Guide], page 15, section "Sprint Goal"
[Scrum Guide], page 9, section "Sprint"
[Scrum Guide], page 16, section "Cancelling a Sprint"