I was just thinking how someone must have grown up in a slave holding family and changed their views, and had to make a dramatic lifestyle change to support these new views. If there aren’t any cases of people freeing all their slaves because of their values, why not?
EDIT: this is not meant to diminish the impact of slavery or the responsibility of those participating in it. A few people freeing their slaves does not fix the harm done, nor does it mitigate the atrocities of slavery.
Yes, there are examples of it, but they were few and far between. I've written about one case previously, originally in a follow-up comment to another answer, and I'll repost that here.
James Birney would be the one of the more famous examples of this. Born in Kentucky, he moved to Alabama and owned a cotton plantation there with several dozen enslaved workers. Over time he started to change his mind, first becoming a colonizationist, than in favor of gradual emancipation, and finally coming to identify as an abolitionist and arguing for immediate emancipation, and 'walking the walk' by freeing what remaining enslaved people he held. I'm unclear if he did so for all his former human chattel, but the final enslaved persons he manumitted - his body servant Michael and his family - in 1834 he paid back wages, with interest, for what he would have earned as a freedman over those years.
He would run for President on that platform in 1840 and 1844 on the Liberty Party ticket. Describing the reasoning of Birney, Jennifer Garman proves an excellent summary of it, but also I would argue provides a very clear argument for the broader frame we're discussing this under, as the argument being made here is not one of modern academia looking back, but one that anti-slavery activists were making at the time as well:
Bimey was first a supporter of the attempt to transport ex-slaves back to Africa. As an agent of American Colonization Society, he toured the South attempt to promote its beliefs. However, Birney came to realize the following:
It is to be feared that we, who have been supporters of colonization, have, through ignorance, been instrumental in prolonging, at least through one lifetime the dark reign of slavery on the earth, and in sending one generation of our fellow men, weeping witnesses of its bitterness, to a comfortless grave!
Bimey was also a critic of gradual emancipation and argued that it created no guilt for the slaveholder as well as angered the slaves who felt that nothing was being done for their rights, but rather for the benefit of their masters. This finally led Birney to support immediate abolition as the method that most fully realized the principles of Christianity. He recognized that the slaves have a right to freedom and it was his Christian duty to secure it for both of them.
Birney is not the only example of this, but a prominent one, stands as an example of what actually treating ones slaves as fellow human beings entailed.
For more on Birney, see:
Rogers, D. Laurence. Apostles of Equality: The Birneys, the Republicans, and the Civil War. Michigan State University Press, 2011.
Garman, Jennifer. "William Lloyd Garrison and James Birney: Two Opposing Views on the Abolition Movement." Wittenburg History Journal (1993): 21.