Who does not need a sponsor?
If you can document that you have at least NOK 500 per day during your stay in Norway and the Schengen area, you do not need a sponsorship form. You can document this by presenting bank statements.
Acting as a financial sponsor is not the same as guaranteeing that the person visiting you will leave Norway once the visit is over. As the party receiving the visitor, it is not possible for you to provide such a guarantee. The immigration authorities assess whether it is likely that a person who has applied for a visa will return once the visit is over, based on an assessment of how strong their ties are to their country of origin/residence.
There are no advantages to providing a sponsorship form if you have enough money. On the contrary, including unnecessary documentation with your application will make it take longer to process your application because we will have more documentation to review.