Back in the early days of self-publishing, it was generally held that self-published book authors did not need a literary agent.
Even today, many self-published authors choose to release their books on their own because they don’t want to pay the fees associated with literary agencies. Also, they want to keep a larger percentage of their royalties.
But something interesting is starting to happen in the publishing industry. Literary agents are increasingly willing to work with authors who prefer to self-publish—and who have little to no interest at all in traditional publishing.
This is not a widespread trend yet, but it is something to watch.